gccrs: Fix non canonical type bug with tuples

gccrs: Fix non canonical type bug with tuples

When working on rpit we needed to change to use a monomorphized clone of
the result of function calls. This ended up causing a verify gimple issue
with tuples because:

  fn test<A, B>(a: A, b: B) -> (A, B)

When passing for example:

  let a = test::<i32, i32> (123, 456) -> (A=i32, B=i32)

The resulting gimple types became:

  const struct (A=i32, B=i32) vs struct (i32, i32)

We removed the VIEW_CONVERT_EXPR support to auto fix this stuff a good
while ago because it hides these kinds of issues because the type hasher
included the A=i32, B=i32 vs the i32, i32 name so updating this to use
get_name instead keeps the naming the same as well as the fields meaning
these types are 100% equivilant and therefore no conversion is required.
This only occurs because tuples are not named types we should really add
more rust specific info on our gimple TYPES.

gcc/rust/ChangeLog:

	* backend/rust-compile-type.cc (TyTyResolveCompile::visit): use get_name
	* typecheck/rust-tyty.cc (TupleType::get_name): likewise

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