Remove some no-longer-needed workarounds in libc++abi

Remove some no-longer-needed workarounds in libc++abi

This CL:
* Removes libc++abi_warnings to workaround [1], since that bug was
  fixed
* Makes libc++abi always a source_set, and only excludes
  cxa_thread_atexit.cpp on mac (see [2] for context).
* Limits the visibility of libc++abi to libc++.  This is to prevent
  abusing including it like in [3].

[1] https://bugs.llvm.org/show_bug.cgi?id=25978
[2] https://bugs.llvm.org/show_bug.cgi?id=33272
[3] https://chromium.googlesource.com/chromium/deps/icu.git/+/2341038bf72869a5683a893a2b319a48ffec7f62

R=hans@chromium.org

Committed: b7a35318665f61f31e811e8cafba44c9c2c52132

[Tom Anderson, 2017-06-05 23:10:01]

Description was changed from

==========
Remove some no-longer-needed workarounds in libc++abi

R=hans@chromium.org
==========

to

==========
Remove some no-longer-needed workarounds in libc++abi

This CL:
* Removes libc++abi_warnings to workaround [1], since that bug was
  fixed
* Makes libc++abi always a source_set, and only excludes
  cxa_thread_atexit.cpp on mac (see [2] for context).
* Limits the visibility of libc++abi to libc++.  This is to prevent
  abusing including it like in [3].

[1] http://llvm.org/PR25978
[2] https://bugs.llvm.org/show_bug.cgi?id=33272
[3]
https://chromium.googlesource.com/chromium/deps/icu.git/+/2341038bf72869a5683...

R=hans@chromium.org
==========

[Tom Anderson, 2017-06-05 23:10:28]

hans ptal

[hans, 2017-06-05 23:18:48]

lgtm

Ultra nit: consistent URLs for the LLVM bug tracker in the commit message? :-)

[Tom Anderson, 2017-06-05 23:20:11]

Description was changed from

==========
Remove some no-longer-needed workarounds in libc++abi

This CL:
* Removes libc++abi_warnings to workaround [1], since that bug was
  fixed
* Makes libc++abi always a source_set, and only excludes
  cxa_thread_atexit.cpp on mac (see [2] for context).
* Limits the visibility of libc++abi to libc++.  This is to prevent
  abusing including it like in [3].

[1] http://llvm.org/PR25978
[2] https://bugs.llvm.org/show_bug.cgi?id=33272
[3]
https://chromium.googlesource.com/chromium/deps/icu.git/+/2341038bf72869a5683...

R=hans@chromium.org
==========

to

==========
Remove some no-longer-needed workarounds in libc++abi

This CL:
* Removes libc++abi_warnings to workaround [1], since that bug was
  fixed
* Makes libc++abi always a source_set, and only excludes
  cxa_thread_atexit.cpp on mac (see [2] for context).
* Limits the visibility of libc++abi to libc++.  This is to prevent
  abusing including it like in [3].

[1] https://bugs.llvm.org/show_bug.cgi?id=25978
[2] https://bugs.llvm.org/show_bug.cgi?id=33272
[3]
https://chromium.googlesource.com/chromium/deps/icu.git/+/2341038bf72869a5683...

R=hans@chromium.org
==========

[Tom Anderson, 2017-06-05 23:20:35]

On 2017/06/05 23:18:48, hans wrote:
> lgtm
> 
> Ultra nit: consistent URLs for the LLVM bug tracker in the commit message? :-)

done!

[Tom Anderson, 2017-06-05 23:22:07]

Description was changed from

==========
Remove some no-longer-needed workarounds in libc++abi

This CL:
* Removes libc++abi_warnings to workaround [1], since that bug was
  fixed
* Makes libc++abi always a source_set, and only excludes
  cxa_thread_atexit.cpp on mac (see [2] for context).
* Limits the visibility of libc++abi to libc++.  This is to prevent
  abusing including it like in [3].

[1] https://bugs.llvm.org/show_bug.cgi?id=25978
[2] https://bugs.llvm.org/show_bug.cgi?id=33272
[3]
https://chromium.googlesource.com/chromium/deps/icu.git/+/2341038bf72869a5683...

R=hans@chromium.org
==========

to

==========
Remove some no-longer-needed workarounds in libc++abi

This CL:
* Removes libc++abi_warnings to workaround [1], since that bug was
  fixed
* Makes libc++abi always a source_set, and only excludes
  cxa_thread_atexit.cpp on mac (see [2] for context).
* Limits the visibility of libc++abi to libc++.  This is to prevent
  abusing including it like in [3].

[1] https://bugs.llvm.org/show_bug.cgi?id=25978
[2] https://bugs.llvm.org/show_bug.cgi?id=33272
[3]
https://chromium.googlesource.com/chromium/deps/icu.git/+/2341038bf72869a5683...

R=hans@chromium.org

Committed: b7a35318665f61f31e811e8cafba44c9c2c52132
==========

[Tom Anderson, 2017-06-05 23:22:08]

Committed patchset #3 (id:40001) manually as
b7a35318665f61f31e811e8cafba44c9c2c52132 (presubmit successful).