Handle AR_FULL vs. AR_FULL in dependency checking.

Handle AR_FULL vs. AR_FULL in dependency checking.

Previously, handling of full vs. full references failed to take
AR_FULL vs. AR_FULL into account.  A change in dependency
checking in gcc 10 created a code path that could lead there;
with this patch, this is now correctly handled.

gcc/fortran/ChangeLog:

2020-06-23  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/95812
	* dependency.c (ref_same_as_full_array): Handle case of AR_FULL
	vs. AR_FULL.

gcc/testsuite/ChangeLog:

2020-06-23  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/95812
	* gfortran.dg/dependency_59.f90: New test.