Sync libm with upstream FreeBSD.

Upstream SHA 78599c32efed3247d165302a1fbe8d9203e38974.

Test: treehugger
Change-Id: Ib103d211315e320df89a6f0bcb30cd8ba67dd603
diff --git a/libm/upstream-freebsd/lib/msun/bsdsrc/mathimpl.h b/libm/upstream-freebsd/lib/msun/bsdsrc/mathimpl.h
index e38ea4f..abf2996 100644
--- a/libm/upstream-freebsd/lib/msun/bsdsrc/mathimpl.h
+++ b/libm/upstream-freebsd/lib/msun/bsdsrc/mathimpl.h
@@ -33,7 +33,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)mathimpl.h	8.1 (Berkeley) 6/4/93
- * $FreeBSD: head/lib/msun/bsdsrc/mathimpl.h 325966 2017-11-18 14:26:50Z pfg $
+ * $FreeBSD$
  */
 
 #ifndef _MATHIMPL_H_