Sync libm with upstream FreeBSD.

Upstream SHA 78599c32efed3247d165302a1fbe8d9203e38974.

Test: treehugger
Change-Id: Ib103d211315e320df89a6f0bcb30cd8ba67dd603
diff --git a/libm/upstream-freebsd/lib/msun/src/s_copysignl.c b/libm/upstream-freebsd/lib/msun/src/s_copysignl.c
index cef101e..bd67447 100644
--- a/libm/upstream-freebsd/lib/msun/src/s_copysignl.c
+++ b/libm/upstream-freebsd/lib/msun/src/s_copysignl.c
@@ -25,7 +25,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $FreeBSD: head/lib/msun/src/s_copysignl.c 326219 2017-11-26 02:00:33Z pfg $
+ * $FreeBSD$
  */
 
 #include <math.h>