Revert "Update to FreeBSD libm r336523."

This reverts commit f86ee10278116d211cfb08679416444e0e714cb5.

Incorrect result for fmodf(3.0f, 0f) = 1.0f breaks ART tests.

Bug: 111710419
Test: art/test/testrunner/testrunner.py -b -t 436-rem-float --target
Change-Id: I7eae68fb92740db33415d16418447bcbbd98ecba
diff --git a/libm/upstream-freebsd/lib/msun/src/s_ctanh.c b/libm/upstream-freebsd/lib/msun/src/s_ctanh.c
index d005baf..bd16109 100644
--- a/libm/upstream-freebsd/lib/msun/src/s_ctanh.c
+++ b/libm/upstream-freebsd/lib/msun/src/s_ctanh.c
@@ -66,7 +66,7 @@
  */
 
 #include <sys/cdefs.h>
-__FBSDID("$FreeBSD: head/lib/msun/src/s_ctanh.c 336362 2018-07-17 07:42:14Z bde $");
+__FBSDID("$FreeBSD: head/lib/msun/src/s_ctanh.c 326219 2017-11-26 02:00:33Z pfg $");
 
 #include <complex.h>
 #include <math.h>
@@ -104,8 +104,8 @@
 	 */
 	if (ix >= 0x7ff00000) {
 		if ((ix & 0xfffff) | lx)	/* x is NaN */
-			return (CMPLX(nan_mix(x, y),
-			    y == 0 ? y : nan_mix(x, y)));
+			return (CMPLX((x + 0) * (y + 0),
+			    y == 0 ? y : (x + 0) * (y + 0)));
 		SET_HIGH_WORD(x, hx - 0x40000000);	/* x = copysign(1, x) */
 		return (CMPLX(x, copysign(0, isinf(y) ? y : sin(y) * cos(y))));
 	}