[Configure]: avoid leaking Win32CORE.c into output of extension probing.

diff --git a/Configure b/Configure
index 2d6f7de..5dbd2f3 100755 (executable)
--- a/Configure
+++ b/Configure
@@ -21655,7 +21655,7 @@ find_extensions='
                $ls -1 $xxx > $$.tmp;
                if $contains "\.xs$" $$.tmp > /dev/null 2>&1; then
                    known_extensions="$known_extensions $this_ext";
-               elif $contains "\.c$" $$.tmp; then
+               elif $contains "\.c$" $$.tmp > /dev/null 2>&1; then
                    known_extensions="$known_extensions $this_ext";
                elif $test -d $xxx; then
                    nonxs_extensions="$nonxs_extensions $this_ext";