[testsuite] Add dg-require-stack-check

[testsuite] Add dg-require-stack-check

2017-07-06  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/
	* doc/sourcebuild.texi (Test Directives, Variants of
	dg-require-support): Add documentation for dg-require-stack-check.

	gcc/testsuite/
	* lib/target-supports-dg.exp (dg-require-stack-check): New.
	* lib/target-supports.exp (check_stack_check_available): New.
	* g++.dg/other/i386-9.C: Add dg-require-stack-check.
	* gcc.c-torture/compile/stack-check-1.c: Likewise.
	* gcc.dg/graphite/run-id-pr47653.c: Likewise.
	* gcc.dg/pr47443.c: Likewise.
	* gcc.dg/pr48134.c: Likewise.
	* gcc.dg/pr70017.c: Likewise.
	* gcc.target/aarch64/stack-checking.c: Likewise.
	* gcc.target/arm/stack-checking.c: Likewise.
	* gcc.target/i386/pr48723.c: Likewise.
	* gcc.target/i386/pr55672.c: Likewise.
	* gcc.target/i386/pr67265-2.c: Likewise.
	* gcc.target/i386/pr67265.c: Likewise.
	* gnat.dg/opt49.adb: Likewise.
	* gnat.dg/stack_check1.adb: Likewise.
	* gnat.dg/stack_check2.adb: Likewise.
	* gnat.dg/stack_check3.adb: Likewise.

From-SVN: r250013