gccrs: Add multiple regression test in name resolution

gccrs: Add multiple regression test in name resolution

Local variables and functions or global variables have different
resolution when binded to a variable. This was not covered before, even
though it was handled by the new name resolution. This commit highlight
this behavior from the new name resolution mechanism.

gcc/testsuite/ChangeLog:

	* rust/compile/name_resolution11.rs: New test.
	* rust/compile/name_resolution12.rs: New test.
	* rust/compile/name_resolution13.rs: New test.

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