fortran: Fix setting of array lower bound for named arrays

fortran: Fix setting of array lower bound for named arrays

This patch fixes a case of setting array low-bounds, found for particular uses
of SOURCE=/MOLD=. This adjusts the relevant part in gfc_trans_allocate() to
set e3_has_nodescriptor only for non-named arrays.

2021-12-03  Tobias Burnus  <tobias@codesourcery.com>

gcc/fortran/ChangeLog:

	* trans-stmt.c (gfc_trans_allocate): Set e3_has_nodescriptor to true
	only for non-named arrays.

gcc/testsuite/ChangeLog:

	* gfortran.dg/allocate_with_source_26.f90: Adjust testcase.
	* gfortran.dg/allocate_with_mold_4.f90: New testcase.

(cherry picked from commit 6262e3a22b3d86afc116480bc59a7bb30b0cfd40)