[Reland] Mojo: Eliminate duplicate C API symbols

[Reland] Mojo: Eliminate duplicate C API symbols

This gets rid of the duplicate definitions of public
Mojo C API symbols, instead making mojo/public/c/system
the singular source of these definitions. This allows
targets to be linked against mojo/public libraries
without requiring any additional EDK dependencies at
build time.

To facilitate this the EDK uses the same set of API
thunks as the public library, and the public library
exposes a special embedder API (distinct from the DSO
MojoSetSystemThunks call used by the native app loader)
for setting these thunks. The MojoSetSystemThunks API
is moved to a module which is only linked directly into
app DSOs.

Because mojo/public/c/system and mojo/edk/system are
now both components, and because there are no longer
redundant exports between the two, it's now safe for
targets to depend on either one or both of them as
needed without encountering duplicate definitions.

Also some opportunistic cleanup of Mojo build rules.

Reland of https://codereview.chromium.org/2044023004

Previous failures were caused by the mojo/public/c/system
component using "system" as its name, breaking -lsystem
behavior in some linking scenarios. This reland changes
the output_name of that target.

BUG=612500
TBR=jam@chromium.org

Committed: https://crrev.com/b04b89b524f89a744e2a0e34a1cfedc84d9085c5
Cr-Commit-Position: refs/heads/master@{#398776}

[Ken Rockot(use gerrit already), 2016-06-09 01:13:35]

Description was changed from

==========
[Reland] Mojo: Eliminate duplicate C API symbols

This gets rid of the duplicate definitions of public
Mojo C API symbols, instead making mojo/public/c/system
the singular source of these definitions. This allows
targets to be linked against mojo/public libraries
without requiring any additional EDK dependencies at
build time.

To facilitate this the EDK uses the same set of API
thunks as the public library, and the public library
exposes a special embedder API (distinct from the DSO
MojoSetSystemThunks call used by the native app loader)
for setting these thunks. The MojoSetSystemThunks API
is moved to a module which is only linked directly into
app DSOs.

Because mojo/public/c/system and mojo/edk/system are
now both components, and because there are no longer
redundant exports between the two, it's now safe for
targets to depend on either one or both of them as
needed without encountering duplicate definitions.

Also some opportunistic cleanup of Mojo build rules.

Reland of https://codereview.chromium.org/2044023004

BUG=612500
TBR=jam@chromium.org
==========

to

==========
[Reland] Mojo: Eliminate duplicate C API symbols

This gets rid of the duplicate definitions of public
Mojo C API symbols, instead making mojo/public/c/system
the singular source of these definitions. This allows
targets to be linked against mojo/public libraries
without requiring any additional EDK dependencies at
build time.

To facilitate this the EDK uses the same set of API
thunks as the public library, and the public library
exposes a special embedder API (distinct from the DSO
MojoSetSystemThunks call used by the native app loader)
for setting these thunks. The MojoSetSystemThunks API
is moved to a module which is only linked directly into
app DSOs.

Because mojo/public/c/system and mojo/edk/system are
now both components, and because there are no longer
redundant exports between the two, it's now safe for
targets to depend on either one or both of them as
needed without encountering duplicate definitions.

Also some opportunistic cleanup of Mojo build rules.

Reland of https://codereview.chromium.org/2044023004

Previous failures were caused by the mojo/public/c/system
component using "system" as its name, breaking -lsystem
behavior in some linking scenarios. This reland changes
the output_name of that target.

BUG=612500
TBR=jam@chromium.org
==========

[Ken Rockot(use gerrit already), 2016-06-09 01:20:12]

The CQ bit was checked by rockot@chromium.org

[commit-bot: I haz the power, 2016-06-09 01:20:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2049773004/20001

[commit-bot: I haz the power, 2016-06-09 03:59:08]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-09 04:01:01]

Description was changed from

==========
[Reland] Mojo: Eliminate duplicate C API symbols

This gets rid of the duplicate definitions of public
Mojo C API symbols, instead making mojo/public/c/system
the singular source of these definitions. This allows
targets to be linked against mojo/public libraries
without requiring any additional EDK dependencies at
build time.

To facilitate this the EDK uses the same set of API
thunks as the public library, and the public library
exposes a special embedder API (distinct from the DSO
MojoSetSystemThunks call used by the native app loader)
for setting these thunks. The MojoSetSystemThunks API
is moved to a module which is only linked directly into
app DSOs.

Because mojo/public/c/system and mojo/edk/system are
now both components, and because there are no longer
redundant exports between the two, it's now safe for
targets to depend on either one or both of them as
needed without encountering duplicate definitions.

Also some opportunistic cleanup of Mojo build rules.

Reland of https://codereview.chromium.org/2044023004

Previous failures were caused by the mojo/public/c/system
component using "system" as its name, breaking -lsystem
behavior in some linking scenarios. This reland changes
the output_name of that target.

BUG=612500
TBR=jam@chromium.org
==========

to

==========
[Reland] Mojo: Eliminate duplicate C API symbols

This gets rid of the duplicate definitions of public
Mojo C API symbols, instead making mojo/public/c/system
the singular source of these definitions. This allows
targets to be linked against mojo/public libraries
without requiring any additional EDK dependencies at
build time.

To facilitate this the EDK uses the same set of API
thunks as the public library, and the public library
exposes a special embedder API (distinct from the DSO
MojoSetSystemThunks call used by the native app loader)
for setting these thunks. The MojoSetSystemThunks API
is moved to a module which is only linked directly into
app DSOs.

Because mojo/public/c/system and mojo/edk/system are
now both components, and because there are no longer
redundant exports between the two, it's now safe for
targets to depend on either one or both of them as
needed without encountering duplicate definitions.

Also some opportunistic cleanup of Mojo build rules.

Reland of https://codereview.chromium.org/2044023004

Previous failures were caused by the mojo/public/c/system
component using "system" as its name, breaking -lsystem
behavior in some linking scenarios. This reland changes
the output_name of that target.

BUG=612500
TBR=jam@chromium.org

Committed: https://crrev.com/b04b89b524f89a744e2a0e34a1cfedc84d9085c5
Cr-Commit-Position: refs/heads/master@{#398776}
==========

[commit-bot: I haz the power, 2016-06-09 04:01:02]

Patchset 2 (id:??) landed as
https://crrev.com/b04b89b524f89a744e2a0e34a1cfedc84d9085c5
Cr-Commit-Position: refs/heads/master@{#398776}