Fix bashism in libc.so filename check, and don't unconditionally set _F_S=2,
as it clobbers e.g. _F_S=3.
--- a/configure.ac
+++ b/configure.ac
@@ -124,7 +124,7 @@ AS_CASE([$host_os],
 	[linux*|kfreebsd*-gnu|freebsd*],
 	[
 		libc_name=`ldd /usr/bin/yes | grep 'libc\.' | cut -d ' ' -f 1 | tr -d '\t'`
-		if test "${libc_name}" == ""; then
+		if test "${libc_name}" = ""; then
 			# Default libc on most system.
 			libc_name="libc.so.6"
 		fi
@@ -258,9 +258,6 @@ AX_CHECK_LINK_FLAG([-pie],[LDFLAGS="$LDFLAGS -pie"],[],[])
 AX_CHECK_LINK_FLAG([-z relro],[LDFLAGS="$LDFLAGS -z relro"],[],[])
 AX_CHECK_LINK_FLAG([-z now],[LDFLAGS="$LDFLAGS -z now"],[],[])
 
-dnl Add glibc hardening
-CPPFLAGS="$CPPFLAGS -D_FORTIFY_SOURCE=2"
-
 ##############################################################################
 # 10. Finish up
 ##############################################################################