Catch division by zero errors in array sizes.

Catch division by zero errors in array sizes.

2019-12-30  Thomas Koenig  <tkoenig@gcc.gnu.org>

	Backport from trunk
	PR fortran/92961
	* gfortran.h (gfc_seen_div0): Add declaration.
	* arith.h (gfc_seen_div0): Add definition.
	(eval_intrinsic): For integer division by zero, set gfc_seen_div0.
	* decl.c (variable_decl):  If resolution resp. simplification
	fails for array spec and a division of zero error has been
	seen, return MATCH_ERROR.

2019-12-30  Thomas Koenig  <tkoenig@gcc.gnu.org>

	Backport from trunk
	PR fortran/92961
	* gfortran.dg/arith_divide_2.f90: New test.

From-SVN: r279767