objtool, kcsan: Add kcsan_disable_current() and kcsan_enable_current_nowarn()

Both are safe to be called from uaccess contexts.
Signed-off-by: NMarco Elver <elver@google.com>
Signed-off-by: NPaul E. McKenney <paulmck@kernel.org>

tools/objtool/check.c

@@ -472,6 +472,8 @@ static const char *uaccess_safe_builtin[] = {
 	"kcsan_found_watchpoint",
 	"kcsan_setup_watchpoint",
 	"kcsan_check_scoped_accesses",
+	"kcsan_disable_current",
+	"kcsan_enable_current_nowarn",
 	/* KCSAN/TSAN */
 	"__tsan_func_entry",
 	"__tsan_func_exit",