relax aarch64 stack-clash tests depedence on alloca.h

relax aarch64 stack-clash tests depedence on alloca.h

2020-01-06  Olivier Hainque  <hainque@adacore.com>
	Alexandre Oliva  <oliva@adacore.com>

	* gcc.target/aarch64/stack-check-alloca.h: Remove
	#include alloca.h. #define alloca __builtin_alloca
	instead.
	* gcc.target/aarch64/stack-check-alloca-1.c: Add
	{ dg-require-effective-target alloca }.
	* gcc.target/aarch64/stack-check-alloca-2.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-3.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-4.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-5.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-6.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-7.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-8.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-9.c: Likewise.
	* gcc.target/aarch64/stack-check-alloca-10.c: Likewise.

Co-Authored-By: Alexandre Oliva <oliva@adacore.com>
From-SVN: r280010