Port LTO-related flags to more platforms.

Port LTO-related flags to more platforms.

Specifically:

- Supply -function-sections flag to the gold plugin when targeting ARM.
  Without this flag, LTO can produce a .text section that is larger than
  the maximum call displacement, preventing the linker from relocating calls.

- Move the other gold plugin-specific flag to the same place,
  and add a Mac version.

BUG=469376, 469377
R=thakis@chromium.org

Committed: https://crrev.com/99ee00d89b2ecfc70682d3222014839adfbceab8
Cr-Commit-Position: refs/heads/master@{#321841}

[Nico, 2015-03-21 03:48:24]

lgtm

https://codereview.chromium.org/1024203004/diff/1/build/common.gypi
File build/common.gypi (right):

https://codereview.chromium.org/1024203004/diff/1/build/common.gypi#newcode5964
build/common.gypi:5964: # than the maximum call displacement, preventing the
linker from
Huh, shouldn't this work without special linker flags? This kind of sounds like
a toolchain bug, no? (It's ok to land this in the meantime, but if you agree
please file a bug somewhere upstream and add a link to that here)

[pcc, 2015-03-23 18:17:43]

pcc@google.com changed reviewers:
+ pcc@google.com

[pcc, 2015-03-23 18:17:44]

https://codereview.chromium.org/1024203004/diff/1/build/common.gypi
File build/common.gypi (right):

https://codereview.chromium.org/1024203004/diff/1/build/common.gypi#newcode5964
build/common.gypi:5964: # than the maximum call displacement, preventing the
linker from
On 2015/03/21 03:48:23, Nico wrote:
> Huh, shouldn't this work without special linker flags? This kind of sounds
like
> a toolchain bug, no? (It's ok to land this in the meantime, but if you agree
> please file a bug somewhere upstream and add a link to that here)

Done.

[pcc1, 2015-03-23 18:18:04]

The CQ bit was checked by pcc@chromium.org

[pcc1, 2015-03-23 18:18:04]

The patchset sent to the CQ was uploaded after l-g-t-m from thakis@chromium.org
Link to the patchset: https://codereview.chromium.org/1024203004/#ps20001
(title: "Add link to LLVM bug")

[commit-bot: I haz the power, 2015-03-23 18:18:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1024203004/20001

[commit-bot: I haz the power, 2015-03-23 20:50:05]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-03-23 20:51:28]

Patchset 2 (id:??) landed as
https://crrev.com/99ee00d89b2ecfc70682d3222014839adfbceab8
Cr-Commit-Position: refs/heads/master@{#321841}