Add support for compiler instrumentation with non-default ASan scale

Add support for compiler instrumentation with non-default ASan scale

	* asan.c (asan_clear_shadow): Adjust for the custom ASAN_SHADOW_SHIFT.
	(asan_redzone_buffer::emit_redzone_byte): Same.
	(asan_redzone_buffer): New assert.
	(asan_emit_stack_protection): New asserts for custom ASAN_SHADOW_SHIFT.
	(asan_emit_stack_protection): Additional redzone flush for the high shadow
	granularities.
	(asan_expand_check_ifn): Adjust for custom ASAN_SHADOW_SHIFT.
	(asan_expand_check_ifn): Same.
	* asan.h (ASAN_RED_ZONE_SIZE): Adjust for custom ASAN_SHADOW_SHIFT.
	(ASAN_MIN_RED_ZONE_SIZE): Same.
	* cfgexpand.c (expand_used_vars): Remove cast.

Change-Id: I770677b502d8a83c765d34a1c5217a947d501693