AC_USE_SYSTEM_EXTENSIONS
AC_DEFINE([__USE_BSD], 1, [Enable BSD extensions])
AC_DEFINE([_POSIX_C_SOURCE], 200809L, [Enable POSIX features])
+AC_DEFINE([_DARWIN_C_SOURCE], 1, [Enable Darwin features])
dnl Checks for programs.
AM_PROG_CC_C_O
AM_PROG_AR
AC_PROG_CC
+AC_PROG_CC_C99
AC_PROG_CXX
AC_PROG_CPP
AC_PROG_INSTALL