clang/win: Disable -Wwritable-strings for most cloud_print service targets.

clang/win: Disable -Wwritable-strings for most cloud_print service targets.

Suppresses 4 warnings that look like

In file included from ..\..\cloud_print\service\win\cloud_print_service.cc:32:
..\..\cloud_print/service/win/service_controller.h(28,3) :  warning(clang): ISO C++11 does not allow conversion from string literal to 'TCHAR *' (aka 'wchar_t *') [-Wwritable-strings]
  DECLARE_REGISTRY_APPID_RESOURCEID(IDR_CLOUDPRINTSERVICE,
  ^
C:\b\depot_tools\win_toolchain\vs2013_files/VC/atlmfc/include\atlbase.h(3086,10) :  note(clang): expanded from macro 'DECLARE_REGISTRY_APPID_RESOURCEID'
                return _T(appid); \
                       ^
C:\b\depot_tools\win_toolchain\vs2013_files\win8sdk\bin\..\..\VC\include\tchar.h(2498,21) :  note(clang): expanded from macro '_T'
                    ^
C:\b\depot_tools\win_toolchain\vs2013_files\win8sdk\bin\..\..\VC\include\tchar.h(206,21) :  note(clang): expanded from macro '__T'
                    ^
<scratch space>(20,1) :  note(clang): expanded from here
L"{8013FB7C-2E3E-4992-B8BD-05C0C4AB0627}"
^
1 warning generated.

BUG=82385
Committed: https://crrev.com/4c11a965b4484a9f339491b70b2860a3c5b2f135
Cr-Commit-Position: refs/heads/master@{#302471}

[Nico, 2014-11-03 18:57:29]

thakis@chromium.org changed reviewers:
+ vitalybuka@chromium.org

[Vitaly Buka (NO REVIEWS), 2014-11-03 19:25:18]

The CQ bit was checked by vitalybuka@chromium.org

[Vitaly Buka (NO REVIEWS), 2014-11-03 19:25:18]

lgtm

[commit-bot: I haz the power, 2014-11-03 19:26:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/686683004/1

[commit-bot: I haz the power, 2014-11-03 20:07:28]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-03 20:08:01]

Patchset 1 (id:??) landed as
https://crrev.com/4c11a965b4484a9f339491b70b2860a3c5b2f135
Cr-Commit-Position: refs/heads/master@{#302471}