Sync libm with upstream FreeBSD.

Upstream SHA 78599c32efed3247d165302a1fbe8d9203e38974.

Test: treehugger
Change-Id: Ib103d211315e320df89a6f0bcb30cd8ba67dd603
diff --git a/libm/upstream-freebsd/lib/msun/src/math_private.h b/libm/upstream-freebsd/lib/msun/src/math_private.h
index bc3d516..b91b54c 100644
--- a/libm/upstream-freebsd/lib/msun/src/math_private.h
+++ b/libm/upstream-freebsd/lib/msun/src/math_private.h
@@ -11,7 +11,7 @@
 
 /*
  * from: @(#)fdlibm.h 5.1 93/09/24
- * $FreeBSD: head/lib/msun/src/math_private.h 336663 2018-07-24 10:10:16Z bde $
+ * $FreeBSD$
  */
 
 #ifndef _MATH_PRIVATE_H_