Avoid warning about BSD_SOURCE on glibc >= 2.20

Commit id c941736c92fa3a319221f65f6755659b2a5e0a20
removed support for _BSD_SOURCE in favor of _DEFAULT_SOURCE.
This commit introduces support for glibc >= 2.20.

_BSD_SOURCE is not ignored, glibc just emits a warning and then
defines _DEFAULT_SOURCE itself. The warning fails the build
because of -Werror.

Change-Id: I9a72ef419678ab1b76174c9481550af8954c2be4
See: https://sourceware.org/git/?p=glibc.git;a=commit;f=include/features.h;h=c941736c92fa3a319221f65f6755659b2a5e0a20
See: https://sourceware.org/git/?p=glibc.git;a=commit;f=include/features.h;h=ade40b10ff5fa59a318cf55b9d8414b758e8df78
Signed-off-by: Arthur Gautier <superbaloo@gmail.com>
1 file changed