use-after-scope fallout

	PR testsuite/78242
	* g++.dg/asan/use-after-scope-4.C: New test.
	* g++.dg/asan/use-after-scope-types-4.C: Update scanned pattern.
	* gcc.dg/asan/use-after-scope-8.c: Remove.
	PR testsuite/78242
	* dbgcnt.def: Add new debug counter asan_use_after_scope.
	* gimplify.c (gimplify_decl_expr): Do not sanitize vars
	with a value expr.  Do not add artificial variables to
	live_switch_vars.  Use the debug counter.
	(gimplify_target_expr): Use the debug counter.
	* internal-fn.def: Remove ECF_TM_PURE from ASAN_MARK builtin.
	* sanitizer.def: Set ATTR_NOTHROW_LEAF_LIST to
	BUILT_IN_ASAN_CLOBBER_N and BUILT_IN_ASAN_UNCLOBBER_N.

From-SVN: r241961