Sync libm with upstream FreeBSD.

Upstream SHA 78599c32efed3247d165302a1fbe8d9203e38974.

Test: treehugger
Change-Id: Ib103d211315e320df89a6f0bcb30cd8ba67dd603
diff --git a/libm/upstream-freebsd/lib/msun/src/s_scalbn.c b/libm/upstream-freebsd/lib/msun/src/s_scalbn.c
index 52b0d27..b048b05 100644
--- a/libm/upstream-freebsd/lib/msun/src/s_scalbn.c
+++ b/libm/upstream-freebsd/lib/msun/src/s_scalbn.c
@@ -11,7 +11,7 @@
  */
 
 #include <sys/cdefs.h>
-__FBSDID("$FreeBSD: head/lib/msun/src/s_scalbn.c 306409 2016-09-28 14:48:34Z emaste $");
+__FBSDID("$FreeBSD$");
 
 /*
  * scalbn (double x, int n)