Fix bugs relating to flexibly-sized objects in nios2 backend.

Fix bugs relating to flexibly-sized objects in nios2 backend.

2019-12-01  Sandra Loosemore  <sandra@codesourcery.com>

	Fix bugs relating to flexibly-sized objects in nios2 backend.

	PR target/92499

	gcc/c/
	* c-decl.c (flexible_array_type_p): Move to common code.

	gcc/
	* config/nios2/nios2.c (nios2_in_small_data_p): Do not consider
	objects of flexible types to be small if they have internal linkage
	or are declared extern.
	* config/nios2/nios2.h (ASM_OUTPUT_ALIGNED_LOCAL): Replace with...
	(ASM_OUTPUT_ALIGNED_DECL_LOCAL): ...this.  Use targetm.in_small_data_p
	instead of the size of the object initializer.
	* tree.c (flexible_array_type_p): Move from C front end, and
	generalize to handle fields in non-C structures.
	* tree.h (flexible_array_type_p): Declare.

	gcc/testsuite/
	* gcc.target/nios2/pr92499-1.c: New.
	* gcc.target/nios2/pr92499-2.c: New.
	* gcc.target/nios2/pr92499-3.c: New.

From-SVN: r278891