Sync libm with upstream FreeBSD.

Upstream SHA 78599c32efed3247d165302a1fbe8d9203e38974.

Test: treehugger
Change-Id: Ib103d211315e320df89a6f0bcb30cd8ba67dd603
diff --git a/libm/upstream-freebsd/lib/msun/src/e_atan2l.c b/libm/upstream-freebsd/lib/msun/src/e_atan2l.c
index 8f80acc..94ebdec 100644
--- a/libm/upstream-freebsd/lib/msun/src/e_atan2l.c
+++ b/libm/upstream-freebsd/lib/msun/src/e_atan2l.c
@@ -14,7 +14,7 @@
  */
 
 #include <sys/cdefs.h>
-__FBSDID("$FreeBSD: head/lib/msun/src/e_atan2l.c 336362 2018-07-17 07:42:14Z bde $");
+__FBSDID("$FreeBSD$");
 
 /*
  * See comments in e_atan2.c.