autoconf: Only _GNU_SOURCE feature test macro needed on gnu systems
According to feature_test_macros(7), _GNU_SOURCE encompasses all the
other feature macros we were setting, so we can just dispose of them.
diff --git a/configure.ac b/configure.ac
index 6a99f30..33c1072 100644
--- a/configure.ac
+++ b/configure.ac
@@ -84,10 +84,7 @@
AC_SUBST([DEFINES])
case "$host_os" in
*-gnu*)
-if test "x$GCC" = xyes; then
- DEFINES="$DEFINES -D_POSIX_SOURCE -D_POSIX_C_SOURCE=199309L -D_BSD_SOURCE"
-fi
- DEFINES="$DEFINES -D_SVID_SOURCE -D_GNU_SOURCE -DPTHREADS"
+ DEFINES="$DEFINES -D_GNU_SOURCE -DPTHREADS"
;;
solaris*)
DEFINES="$DEFINES -DPTHREADS -DSVR4"