Make sure GetRegEx returns something gnuplot can deal with (a number, not
a ?) so that graphs don't bail if something fails in a test.

llvm-svn: 14344
diff --git a/llvm/utils/NightlyTest.pl b/llvm/utils/NightlyTest.pl
index 4543a5a..57c2201 100755
--- a/llvm/utils/NightlyTest.pl
+++ b/llvm/utils/NightlyTest.pl
@@ -101,7 +101,7 @@
   if (defined($1)) {
     return $1;
   }
-  return "?";
+  return "0";
 }
 
 sub AddRecord {