contrib: Add in the default push rule which was overridden

contrib: Add in the default push rule which was overridden

When we add a push rule, the default rule gets removed, so add that in
explicitly.  This needs to come last since otherwise it would match
the custom redirecting rules we have for personal and vendor
sub-spaces.

I also noticed that the push rule for the vendor subspace still had
a force push default.  We don't want that so remove it.

	* gcc-git-customization.sh: Add back the default rule that
	is lost by adding a custom push rule.
	* git-fetch-vendor.sh: Likewise, also remove '+' from push specs.