pre-configure/gnu-configure-asneeded.sh: do nothing if configure_script does not exist.

common/hooks/pre-configure/gnu-configure-asneeded.sh

@@ -3,6 +3,9 @@
 hook() {
 	: ${configure_script:=./configure}
 
+	if [ ! -f ${configure_script} ]; then
+		return 0
+	fi
 	# http://lists.gnu.org/archive/html/libtool-patches/2004-06/msg00002.html
 	if [ -z "$broken_as_needed" -a "$build_style" = "gnu-configure" ]; then
 		sed -i "s/^\([ \t]*tmp_sharedflag\)='-shared'/\1='-shared -Wl,--as-needed'/" ${configure_script}