gccrs: Reinject Self parameter in new resolver

gccrs: Reinject Self parameter in new resolver

The old resolver injected a Self generic parameter in order to help the
trait solver. This is clearly sketchy at best and should be fixed in
the future.

gcc/rust/ChangeLog:

	* resolve/rust-toplevel-name-resolver-2.0.cc (TopLevel::visit): Add
	Self generic parameter injection and a warning.
	* resolve/rust-toplevel-name-resolver-2.0.h: Add function prototype.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>