gccrs: Resolve nested macro definition

gccrs: Resolve nested macro definition

We need to collect the early resolver's macros error to emit them at a
later stage after further expansion in order to retrieve macros defined
by other macro invocations.
Register some mappings for macro invocations and macro definitions.

gcc/rust/ChangeLog:

	* resolve/rust-early-name-resolver-2.0.cc (Early::visit):
	Collect error instead of emitting it. Also add invocation
	registration.
	* resolve/rust-early-name-resolver-2.0.h (std::function<void):
	Add type definition for collection.
	* resolve/rust-toplevel-name-resolver-2.0.cc (TopLevel::visit):
	Register macro rule definition in mappings.
	* rust-session-manager.cc (Session::expansion): Add macro
	resolve error collection.

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