Add librt to default libs on linux

Add librt to default libs on linux

It's needed by clock_gettime() on glibc < 2.17, and that function is
called in various places in the codebase. This library is part of glibc,
so just put in the default toolchain libs so we get it everywhere.

It fixes the following build error:

gn gen out_gn_ozone --args='use_ozone=true toolkit_views=false is_component_build=true'
ninja -C out_gn_ozone content_shell

../ui/gl/sync_control_vsync_provider.cc:70: error: undefined reference to
'clock_gettime'
../ui/gl/sync_control_vsync_provider.cc:71: error: undefined reference to
'clock_gettime'

Committed: https://crrev.com/651aab406b2684042fcb0d87fe5f27a68bd8764b
Cr-Commit-Position: refs/heads/master@{#368383}

[spang, 2016-01-06 22:00:42]

The CQ bit was checked by spang@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-01-06 22:03:06]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1565983002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1565983002/1

[spang, 2016-01-06 22:48:28]

spang@chromium.org changed reviewers:
+ brettw@chromium.org

[commit-bot: I haz the power, 2016-01-06 23:00:51]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-01-06 23:00:51]

Dry run: This issue passed the CQ dry run.

[brettw, 2016-01-07 19:03:19]

brettw@chromium.org changed reviewers:
+ thestig@chromium.org

[brettw, 2016-01-07 19:03:20]

+Lei: do you think everything should depend in "rt" on Linux, or should we fix
this by just adding "rt" to the dependencies in ui/gl?

[spang, 2016-01-07 22:29:18]

On 2016/01/07 19:03:20, brettw wrote:
> +Lei: do you think everything should depend in "rt" on Linux, or should we fix
> this by just adding "rt" to the dependencies in ui/gl?

Happy to do either way. I did it this way because otherwise it's a source of
inconsistency between glibc < 2.17 and glibc 2.17 - we don't have a checker for
these. And we always get it anyway via //base and libevent; it's not exactly
optional.

Timekeeping seems just as critical as library loading, which does get linked
unconditionally.

Anyway, there's a couple places in addition to //ui/gl should have a direct
dependency if we got that route.

[Lei Zhang, 2016-01-07 22:30:08]

On 2016/01/07 19:03:20, brettw wrote:
> +Lei: do you think everything should depend in "rt" on Linux, or should we fix
> this by just adding "rt" to the dependencies in ui/gl?

Either is fine. The former is just more convenient since librt is basically
available everywhere.

[brettw, 2016-01-07 22:48:05]

okay, lgtm then.

[spang, 2016-01-08 01:31:24]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2016-01-08 01:33:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1565983002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1565983002/1

[commit-bot: I haz the power, 2016-01-08 01:43:28]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-01-08 01:43:29]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[spang, 2016-01-08 18:26:04]

spang@chromium.org changed reviewers:
+ xhwang@chromium.org

[spang, 2016-01-08 18:26:09]

+xhwang@chromium.org for widevine

[xhwang, 2016-01-08 18:34:23]

lgtm

[spang, 2016-01-08 18:35:12]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2016-01-08 18:36:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1565983002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1565983002/1

[commit-bot: I haz the power, 2016-01-08 18:43:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-01-08 18:44:01]

Description was changed from

==========
Add librt to default libs on linux

It's needed by clock_gettime() on glibc < 2.17, and that function is
called in various places in the codebase. This library is part of glibc,
so just put in the default toolchain libs so we get it everywhere.

It fixes the following build error:

gn gen out_gn_ozone --args='use_ozone=true toolkit_views=false
is_component_build=true'
ninja -C out_gn_ozone content_shell

../ui/gl/sync_control_vsync_provider.cc:70: error: undefined reference to
'clock_gettime'
../ui/gl/sync_control_vsync_provider.cc:71: error: undefined reference to
'clock_gettime'
==========

to

==========
Add librt to default libs on linux

It's needed by clock_gettime() on glibc < 2.17, and that function is
called in various places in the codebase. This library is part of glibc,
so just put in the default toolchain libs so we get it everywhere.

It fixes the following build error:

gn gen out_gn_ozone --args='use_ozone=true toolkit_views=false
is_component_build=true'
ninja -C out_gn_ozone content_shell

../ui/gl/sync_control_vsync_provider.cc:70: error: undefined reference to
'clock_gettime'
../ui/gl/sync_control_vsync_provider.cc:71: error: undefined reference to
'clock_gettime'

Committed: https://crrev.com/651aab406b2684042fcb0d87fe5f27a68bd8764b
Cr-Commit-Position: refs/heads/master@{#368383}
==========

[commit-bot: I haz the power, 2016-01-08 18:44:04]

Patchset 1 (id:??) landed as
https://crrev.com/651aab406b2684042fcb0d87fe5f27a68bd8764b
Cr-Commit-Position: refs/heads/master@{#368383}