pass clangcl compile options to ignore warnings in gflags.cc

pass clangcl compile options to ignore warnings in gflags.cc

R=kjellander@webrtc.org, ajm@webrtc.org
BUG=webrtc:760
Committed: https://crrev.com/b608eb865e9fa0c9e3e78f1ff036341622ee7819
Cr-Commit-Position: refs/heads/master@{#10440}

[kjellander_webrtc, 2015-10-28 12:09:00]

kjellander@webrtc.org changed reviewers:
+ kjellander@webrtc.org

[kjellander_webrtc, 2015-10-28 12:09:01]

Generally looks good but you have to make the newly added code only apply when
clang==1 on Windows. See my comment.

https://codereview.webrtc.org/1426883002/diff/1/third_party/gflags/gflags.gyp
File third_party/gflags/gflags.gyp (right):

https://codereview.webrtc.org/1426883002/diff/1/third_party/gflags/gflags.gyp...
third_party/gflags/gflags.gyp:66: 'msvs_settings': {
After looking at the trybot failure for regular (non-Clang) build on Win it
seems you have to put this into a condition like 'OS=="win" and clang==1': 

[302/2847] LIB obj\third_party\libjpeg_turbo\libjpeg.lib
FAILED: ninja -t msvc -e environment.x64 -- E:\b\build\goma/gomacc
"E:\b\depot_tools\win_toolchain\vs2013_files\VC\bin\amd64\cl.exe" /nologo
/showIncludes /FC @obj\third_party\gflags\src\windows\gflags.port.obj.rsp /c
..\..\third_party\gflags\src\windows\port.cc
/Foobj\third_party\gflags\src\windows\gflags.port.obj
/Fdobj\third_party\gflags\gflags.cc.pdb 
cl : Command line error D8021 : invalid numeric argument
'/Wno-unused-local-typedef'

[kjellander_webrtc, 2015-10-28 17:54:58]

lgtm

no need to run all those trybots for this patch (as we're kind of low on trybot
resources). 

Feel free to commit it manually.

[fbarchard1, 2015-10-28 17:59:54]

Committed patchset #3 (id:40001) manually as
b608eb865e9fa0c9e3e78f1ff036341622ee7819 (presubmit successful).

[commit-bot: I haz the power, 2015-10-28 17:59:56]

Patchset 3 (id:??) landed as
https://crrev.com/b608eb865e9fa0c9e3e78f1ff036341622ee7819
Cr-Commit-Position: refs/heads/master@{#10440}