gccrs: Track associated type generics

gccrs: Track associated type generics

This fixes an issue with our qualified type-paths if we point to a generic
associated type this needs to either use the placeholder type on the trait
reference or use the impl-type but apply the generics.

gcc/rust/ChangeLog:

	* typecheck/rust-hir-trait-reference.h: update prototype
	* typecheck/rust-hir-trait-resolve.cc: add generic args as an out param
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::visit): use the generics

Signed-off-by: Philip Herron <herron.philip@googlemail.com>