Fortran: Fix c_associated argument checks.

Fortran: Fix c_associated argument checks.

	PR fortran/120049

gcc/fortran/ChangeLog:

	* check.cc (gfc_check_c_associated): Use new helper functions.
	Only call check_c_ptr_1 if optional c_ptr_2 tests succeed.
	(check_c_ptr_1): Handle only c_ptr_1 checks.
	(check_c_ptr_2): Expand checks for c_ptr_2 and handle cases
	where there is no derived pointer in the gfc_expr and check
	the inmod_sym_id only if it exists. Rephrase error message.
	* misc.cc (gfc_typename): Handle the case for BT_VOID rather
	than throw an internal error.

gcc/testsuite/ChangeLog:

	* gfortran.dg/pr120049_a.f90: Update test directives.
	* gfortran.dg/pr120049_b.f90: Update test directives
	* gfortran.dg/pr120049_2.f90: New test.
	* gfortran.dg/c_f_pointer_tests_6.f90: Adjust dg-error
	directive.

	Co-Authored-By: Steve Kargl <kargl@gcc.gnu.org>
(cherry picked from commit 42983ffde6612b7f8a4e7ab3e76fa8b0d136e854)