aarch64: Add a couple of extra stack-protector tests

These tests were inspired by corresponding arm ones.  They already pass.

gcc/testsuite/
	* gcc.target/aarch64/stack-protector-3.c: New test.
	* gcc.target/aarch64/stack-protector-4.c: Likewise.

gcc/testsuite/gcc.target/aarch64/stack-protector-3.c

@@ -0,0 +1,45 @@
+/* { dg-do run } */
+/* { dg-require-effective-target fstack_protector } */
+/* { dg-options "-fstack-protector-all -O2" } */
+
+extern volatile long *stack_chk_guard_ptr;
+
+void __attribute__ ((noipa))
+f (void)
+{
+  volatile int x;
+  /* Munging the contents of __stack_chk_guard should trigger a
+     stack-smashing failure for this function.  */
+  *stack_chk_guard_ptr += 1;
+}
+
+#define CHECK(REG) "\tcmp\tx0, " #REG "\n\tbeq\t1f\n"
+
+asm (
+"	.pushsection .data\n"
+"	.align	3\n"
+"stack_chk_guard_ptr:\n"
+#if __ILP32__
+"	.word	__stack_chk_guard\n"
+#else
+"	.xword	__stack_chk_guard\n"
+#endif
+"	.weak	__stack_chk_guard\n"
+"__stack_chk_guard:\n"
+"	.word	0xdead4321\n"
+"	.word	0xbeef8765\n"
+"	.text\n"
+"	.type	__stack_chk_fail, %function\n"
+"__stack_chk_fail:\n"
+"	mov	x0, #0\n"
+"	b	exit\n"
+"	.size	__stack_chk_fail, .-__stack_chk_fail\n"
+"	.popsection"
+);
+
+int
+main (void)
+{
+  f ();
+  __builtin_abort ();
+}

gcc/testsuite/gcc.target/aarch64/stack-protector-4.c

@@ -0,0 +1,6 @@
+/* { dg-do run } */
+/* { dg-require-effective-target fstack_protector } */
+/* { dg-require-effective-target fpic } */
+/* { dg-options "-fstack-protector-all -O2 -fpic" } */
+
+#include "stack-protector-3.c"