Use _POSIX_C_SOURCE not _BSD_SOURCE.

_BSD_SOURCE has been deprecated (see bug). The manpage for printf
suggests that any _POSIX_C_SOURCE >= 200112L is also sufficient to bring
in the needed declarations and the bug reporter confirms that it's
sufficient for him.

https://code.google.com/p/chromium/issues/detail?id=419859

Change-Id: Ifc053f11c5aa1df35aae8e952d2c73a7f4599ec2
Reviewed-on: https://boringssl-review.googlesource.com/1890
Reviewed-by: Adam Langley <agl@google.com>
5 files changed