Fortran: function results never have the ALLOCATABLE attribute [PR109500]

Fortran: function results never have the ALLOCATABLE attribute [PR109500]

Fortran 2018 8.5.3 (ALLOCATABLE attribute) explains in Note 1 that the
result of referencing a function whose result variable has the ALLOCATABLE
attribute is a value that does not itself have the ALLOCATABLE attribute.

gcc/fortran/ChangeLog:

	PR fortran/109500
	* interface.cc (gfc_compare_actual_formal): Reject allocatable
	functions being used as actual argument for allocable dummy.

gcc/testsuite/ChangeLog:

	PR fortran/109500
	* gfortran.dg/allocatable_function_11.f90: New test.

Co-authored-by: Steven G. Kargl <kargl@gcc.gnu.org>