[fuchsia] GN build support for Fuchsia OS and fuchsia_test target

[fuchsia] GN build support for Fuchsia OS and fuchsia_test target

This adds a GN target for the 'fuchsia_test' executable and teaches
the GN build about is_fuchsia. Key differences:

*) There's not currently a dart:io implementation for Fuchsia
*) Fuchsia's toolchain currently doesn't support (or need) ldl or lpthread
*) Fuchsia's buildconfig doesn't currently set the is_asan variable

Committed: https://github.com/dart-lang/sdk/commit/e27b49fc80f434f790875707df9a4b8958e4b2dc

[jamesr, 2016-07-14 19:47:44]

jamesr@chromium.org changed reviewers:
+ zra@google.com

[jamesr, 2016-07-14 19:47:45]

https://codereview.chromium.org/2149953003/diff/1/runtime/bin/BUILD.gn
File runtime/bin/BUILD.gn (right):

https://codereview.chromium.org/2149953003/diff/1/runtime/bin/BUILD.gn#newcode9
runtime/bin/BUILD.gn:9: if (!is_fuchsia) {
this is needed since the only reference to this variable is in a target i have
disabled as it doesn't work in fuchsia yet and the boringssl rules in
dart-lang/sdk/third_party/boringssl don't know about fuchsia yet. i could leave
a comment here if it'd be helpful for other devs

https://codereview.chromium.org/2149953003/diff/1/runtime/bin/BUILD.gn#newcod...
runtime/bin/BUILD.gn:213: if (!is_fuchsia) {
this is over-broad but works (for now at least)

https://codereview.chromium.org/2149953003/diff/1/runtime/vm/BUILD.gn
File runtime/vm/BUILD.gn (right):

https://codereview.chromium.org/2149953003/diff/1/runtime/vm/BUILD.gn#newcode6
runtime/vm/BUILD.gn:6: if (!is_fuchsia) {
this is a bug in our toolchain definition. happy to delete this as soon as we
fix that bug and/or leave a comment here explaining

[zra, 2016-07-14 22:01:33]

Description was changed from

==========
[fuchsia] GN build support for Fuchsia OS and fuchsia_test target

This adds a GN target for the 'fuchsia_test' executable and teaches
the GN build about is_fuchsia. Key differences:

*) There's not currently a dart:io implementation for Fuchsia
*) Fuchsia's toolchain currently doesn't support (or need) ldl or lpthread
*) Fuchsia's buildconfig doesn't currently set the is_asan variable
==========

to

==========
[fuchsia] GN build support for Fuchsia OS and fuchsia_test target

This adds a GN target for the 'fuchsia_test' executable and teaches
the GN build about is_fuchsia. Key differences:

*) There's not currently a dart:io implementation for Fuchsia
*) Fuchsia's toolchain currently doesn't support (or need) ldl or lpthread
*) Fuchsia's buildconfig doesn't currently set the is_asan variable

Committed:
https://github.com/dart-lang/sdk/commit/e27b49fc80f434f790875707df9a4b8958e4b2dc
==========

[zra, 2016-07-14 22:01:35]

Committed patchset #2 (id:20001) manually as
e27b49fc80f434f790875707df9a4b8958e4b2dc (presubmit successful).

[zra, 2016-07-14 22:02:59]

lgtm

Had to check for defined(is_fuchsia) in a couple places.