gallivm: give more verbose names to modules

gallivm: give more verbose names to modules

When we had just one module "gallivm" was an appropriate name. But now we have
modules containing all functions for a particular variant, so give it a
corresponding name (this is really just for helping debugging).

Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>