>>533
/usr/include/sys/cdefs.h:273 を
- #if _POSIX_C_SOURCE == 1
+ #if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE == 1
/usr/include/sys/cdefs.h:279 を
- #if _POSIX_C_SOURCE == 2
+ #if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE == 2

な感じにすればいいんじゃない?