Update libm from upstream.

Bug: N/A
Test: ran tests
Change-Id: Ifa03eb36d412a2776208cd2921936be4724e5547
diff --git a/libm/upstream-freebsd/lib/msun/src/s_copysignl.c b/libm/upstream-freebsd/lib/msun/src/s_copysignl.c
index 8d39f84..cef101e 100644
--- a/libm/upstream-freebsd/lib/msun/src/s_copysignl.c
+++ b/libm/upstream-freebsd/lib/msun/src/s_copysignl.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (c) 2004 Stefan Farfeleder
  * All rights reserved.
  *
@@ -23,7 +25,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $FreeBSD$
+ * $FreeBSD: head/lib/msun/src/s_copysignl.c 326219 2017-11-26 02:00:33Z pfg $
  */
 
 #include <math.h>