[PATCH] don't allow invalid --gc options

[Gabor Szabo]

It has biten me so let's make sure invalid --gc options are not allowed.

Index: lib/Parrot/Configure/Options.pm
===================================================================
--- lib/Parrot/Configure/Options.pm     (revision 20963)
+++ lib/Parrot/Configure/Options.pm     (working copy)
@@ -48,6 +48,9 @@
         }
         $data->{$key} = $value;
     }
+    if ($data->{gc} and $data->{gc} !~ /^(gc|libc|malloc|malloc-trace)$/) {
+        croak "Invalid value for 'gc' argument.\nType perl
Configure.pl --help to see available values";
+    }
     if (@short_circuits_seen) {
         # run all the short circuits
         foreach my $sc (@short_circuits_seen) {