Update libm from upstream.

Bug: N/A
Test: ran tests
Change-Id: Ifa03eb36d412a2776208cd2921936be4724e5547
diff --git a/libm/upstream-freebsd/lib/msun/src/s_carg.c b/libm/upstream-freebsd/lib/msun/src/s_carg.c
index ea1a0d7..d0f9ced 100644
--- a/libm/upstream-freebsd/lib/msun/src/s_carg.c
+++ b/libm/upstream-freebsd/lib/msun/src/s_carg.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
  * All rights reserved.
  *
@@ -25,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
+__FBSDID("$FreeBSD: head/lib/msun/src/s_carg.c 326219 2017-11-26 02:00:33Z pfg $");
 
 #include <complex.h>
 #include <math.h>