gpu/khronos_glcts_support: WA suppress compile-time warnings on linux

gpu/khronos_glcts_support: WA suppress compile-time warnings on linux

Add various cflags/cflags_cc and disable clang chromium-style
enforcement on third_party/khronos_glcts sourcecode and support.

This is a workaround for various compile time warnings on desktop
linux (e.g. Ubuntu 12.04) that are treated as errors (i.e. by
-Werror).  The source of these warnings are from the
third_party/khronos_glcts sourcecode.  With these workarounds
the khronos_glcts_test is able to finish compilation.

The plan is to eventually fix the third-party code so we can
remove these workarounds.

BUG=chromium:412865
R=piman@chromium.org, kbr@chromium.org
TBR=piman@chromium.org
TEST=export GYP_DEFINES="internal_khronos_glcts_tests=1"
TEST=gclient runhooks
TEST=ninja -C out/Release khronos_glcts_test
TEST=./out/Release/khronos_glcts_test
TEST=ninja -C out/Debug khronos_glcts_test
TEST=./out/Debug/khronos_glcts_test

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>;

Committed: https://crrev.com/66e31a6c026cd22fa2341d924f5ceb18652ec217
Cr-Commit-Position: refs/heads/master@{#297929}

[U. Artie Eoff, 2014-10-02 01:30:30]

Hello, I'd like you to review my code.

[Ken Russell (switch to Gerrit), 2014-10-02 22:24:33]

Thank you for this patch. I've verified locally that with one build fix to the
GLES2 FBORenderMipmap extension test, these GYP changes let the
khronos_glcts_test binary build on desktop Linux. LGTM

[Ken Russell (switch to Gerrit), 2014-10-02 22:25:05]

Note: that workaround's already been committed to the Chromium copy of the
sources, and I'll submit a patch to Khronos.

[Ken Russell (switch to Gerrit), 2014-10-02 22:25:24]

TBR'ing to piman and CQ'ing.

[Ken Russell (switch to Gerrit), 2014-10-02 22:25:28]

The CQ bit was checked by kbr@chromium.org

[commit-bot: I haz the power, 2014-10-02 22:27:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/615063004/1

[commit-bot: I haz the power, 2014-10-02 22:34:31]

Committed patchset #1 (id:1) as aa7b1548b2ab94c282d4aa41277d11143b82e3b3

[commit-bot: I haz the power, 2014-10-02 22:35:13]

Patchset 1 (id:??) landed as
https://crrev.com/66e31a6c026cd22fa2341d924f5ceb18652ec217
Cr-Commit-Position: refs/heads/master@{#297929}