Fortran: Fixes for F2018 C838 (PR fortran/101334)

Fortran: Fixes for F2018 C838 (PR fortran/101334)

The compiler was failing to diagnose the error required by F2018 C838
when passing an assumed-rank array argument to a non-assumed-rank dummy.
It was also incorrectly giving an error for calls to the 2-argument form
of the ASSOCIATED intrinsic, which is supposed to be permitted by C838.

2021-09-19  Sandra Loosemore  <sandra@codesourcery.com>

	PR fortran/101334

gcc/fortran/
	* check.c (gfc_check_associated): Allow an assumed-rank
	array for the pointer argument.
	* interface.c (compare_parameter): Also give rank mismatch
	error on assumed-rank array.

gcc/testsuite/
	* gfortran.dg/c-interop/c535b-2.f90: Remove xfails.
	* gfortran.dg/c-interop/c535b-3.f90: Likewise.