[PATCH][GCC][AARCH64] Add tests for pointer authentication B-key

[PATCH][GCC][AARCH64] Add tests for pointer authentication B-key

	gcc/testsuite/ChangeLog
	* gcc.target/aarch64/return_address_sign_b_1.c: New file.
	* gcc.target/aarch64/return_address_sign_b_2.c: New file.
	* gcc.target/aarch64/return_address_sign_b_3.c: New file.
	* gcc.target/aarch64/return_address_sign_builtin.c: New file.
	* g++.target/aarch64/return_address_sign_ab_exception.C: New file.
	* g++.target/aarch64/return_address_sign_b_exception.C: New file.

From-SVN: r271954