Sync upstream FreeBSD libm.

Test: treehugger
Change-Id: I583a3e93821d512c975db34fc1610ffd22445d58
diff --git a/libm/upstream-freebsd/lib/msun/src/e_atan2f.c b/libm/upstream-freebsd/lib/msun/src/e_atan2f.c
index 346d767..4ea001d 100644
--- a/libm/upstream-freebsd/lib/msun/src/e_atan2f.c
+++ b/libm/upstream-freebsd/lib/msun/src/e_atan2f.c
@@ -30,7 +30,7 @@
 pi_lo   = -8.7422776573e-08; /* 0xb3bbbd2e */
 
 float
-__ieee754_atan2f(float y, float x)
+atan2f(float y, float x)
 {
 	float z;
 	int32_t k,m,hx,hy,ix,iy;