Use a proper ignore_result() to fix a ftruncate warn_unused_result warning with GCC 4.8.

Use a proper ignore_result() to fix a ftruncate warn_unused_result warning with
GCC 4.8.

BUG=492
R=mark@chromium.org

Committed: https://code.google.com/p/google-breakpad/source/detail?r=1266

[Lei Zhang (chromium)]

In addition to static_cast<void>() being described as ugly in r1027, it also
doesn't work on gcc 4.8.

[Mark Mentovai]

https://breakpad.appspot.com/944003/diff/1/src/common/basictypes.h
File src/common/basictypes.h (right):

https://breakpad.appspot.com/944003/diff/1/src/common/basictypes.h#newcode45
src/common/basictypes.h:45: // that has been marked WARN_UNUSED_RESULT, wrap it
with this. Example:
WARN_UNUSED_RESULT is meaningless in Breakpad.
__attribute__((warn_unused_result)) is GCC/clang-specific, but at least it makes
sense here.

[Mark Mentovai]

LGTM

[Lei Zhang (chromium)]

https://breakpad.appspot.com/944003/diff/1/src/common/basictypes.h
File src/common/basictypes.h (right):

https://breakpad.appspot.com/944003/diff/1/src/common/basictypes.h#newcode45
src/common/basictypes.h:45: // that has been marked WARN_UNUSED_RESULT, wrap it
with this. Example:
On 2013/12/18 16:56:18, Mark Mentovai wrote:
> WARN_UNUSED_RESULT is meaningless in Breakpad.
> __attribute__((warn_unused_result)) is GCC/clang-specific, but at least it
makes
> sense here.

Done.

[Lei Zhang (chromium)]

Committed patchset #2 manually as r1266 (presubmit successful).