Demand for newer POSIX macro

Reason for change: Define _POSIX_C_SOURCE such that it demands correct
posix interfaces, netdb.h declares interfaces such as
getaddrinfo if __USE_POSIX, i.e. POSIX.1:1990 or later.
However, these interfaces were new in the 2001 edition of POSIX
therefore ask for Extension from POSIX.1:2001 since we use addrinfo
structure here.

Change-Id: Icb1c92745d1a0ca958108ae80c270c630628729e
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Reviewed-on: https://boringssl-review.googlesource.com/5253
Reviewed-by: Adam Langley <agl@google.com>
1 file changed