testsuite: Handle --save-temps in schedule-cleanups

Some tests use --save-temps, but schedule-cleanups strictly matches
-save-temps, so we leave many temporary files after validation.
Instead of fixing every offending testcase, it's simpler and
future-proof to make schedule-cleanups handle both --save-temps and
-save-temps.

2020-04-22  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/testsuite/
	* lib/gcc-dg.exp (schedule-cleanups): Accept --save-temps.

gcc/testsuite/ChangeLog

+2020-04-22  Christophe Lyon  <christophe.lyon@linaro.org>
+
+	* lib/gcc-dg.exp (schedule-cleanups): Accept --save-temps.
+
 2020-04-22  Martin Sebor  <msebor@redhat.com>
 
 	PR c++/94510

gcc/testsuite/lib/gcc-dg.exp

@@ -171,7 +171,7 @@ proc schedule-cleanups { opts } {
 	verbose "dg-keep-saved-temps ${keep_saved_temps_suffixes}" 2
     }
     # -save-temps -> cleanup-saved-temps()
-    if [regexp -- {(^|\s+)-save-temps(\s+|$)} $opts] {
+    if [regexp -- {(^|\s+)-?-save-temps(\s+|$)} $opts] {
 	verbose "Cleanup -save-temps seen" 4
 	if [info exists keep_saved_temps_suffixes] {
 	    append finalcode "cleanup-saved-temps ${keep_saved_temps_suffixes}\n"