Fortran: F2018 type(*),dimension(*) with scalars [PR104143]

Assumed-size dummy arguments accept arrays and array elements as actual
arguments. There are also a few exceptions when real scalars are permitted.
Since F2018, this includes scalar arguments to assumed-type dummies; while
type(*) was added in TS29113, this change is only in F2018 itself.

	PR fortran/104143

gcc/fortran/ChangeLog:

	* interface.cc (compare_parameter): Permit scalar args to
	'type(*), dimension(*)'.

gcc/testsuite/ChangeLog:

	* gfortran.dg/c-interop/c407b-2.f90: Remove dg-error.
	* gfortran.dg/assumed_type_16.f90: New test.
	* gfortran.dg/assumed_type_17.f90: New test.