Fortran: Fix same_type_as

Fortran: Fix same_type_as

A test for CLASS(*) + assumed rank was missing; adding a test to
unlimited_polymorphic_1.f03 showed an ICE as backend_decl wasn't
set. While gfc_get_symbol_decl would fix it, the code also assumed
that the class(*) was a variable and could not be a subobject of
a derived type.

	PR fortran/71703
	PR fortran/84007

gcc/fortran/ChangeLog:

	* trans-intrinsic.c (gfc_conv_same_type_as): Fix handling
	of UNLIMITED_POLY.
	* trans.h (gfc_vtpr_hash_get): Renamed prototype to ...
	(gfc_vptr_hash_get): ... this to match function name.

gcc/testsuite/ChangeLog:

	* gfortran.dg/c-interop/c535b-1.f90: Remove wrong comment.
	* gfortran.dg/unlimited_polymorphic_1.f03: Extend.
	* gfortran.dg/unlimited_polymorphic_32.f90: New test.