PR fortran/95979 - ICE in get_kind, at fortran/simplify.c:129

PR fortran/95979 - ICE in get_kind, at fortran/simplify.c:129

Simplification of the elemental intrinsic INDEX with constant array-valued
arguments failed with an ICE or did not reduce to a constant array, depending
also on the presence of the optional KIND argument.  Add a further attempt of
simplification in the case of elemental intrinsics, and make sure the KIND
argument is not removed prematurely during simplification of INDEX.

gcc/fortran/ChangeLog:

	PR fortran/95979
	* expr.c (gfc_check_init_expr): Fix check of return code from
	gfc_intrinsic_func_interface.
	* intrinsic.c (gfc_intrinsic_func_interface): Add further attempt
	of simplification of elemental intrinsics with array arguments.
	* iresolve.c (gfc_resolve_index_func): Keep optional KIND argument
	for simplification of elemental use of INDEX.

gcc/testsuite/ChangeLog:

	PR fortran/95979
	* gfortran.dg/index_4.f90: New test.