Sync libm with upstream FreeBSD.

Upstream SHA 78599c32efed3247d165302a1fbe8d9203e38974.

Test: treehugger
Change-Id: Ib103d211315e320df89a6f0bcb30cd8ba67dd603
diff --git a/libm/upstream-freebsd/lib/msun/src/k_expf.c b/libm/upstream-freebsd/lib/msun/src/k_expf.c
index 5aa5c76..80e629b 100644
--- a/libm/upstream-freebsd/lib/msun/src/k_expf.c
+++ b/libm/upstream-freebsd/lib/msun/src/k_expf.c
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__FBSDID("$FreeBSD: head/lib/msun/src/k_expf.c 326219 2017-11-26 02:00:33Z pfg $");
+__FBSDID("$FreeBSD$");
 
 #include <complex.h>
 
@@ -71,7 +71,7 @@
 float complex
 __ldexp_cexpf(float complex z, int expt)
 {
-	float x, y, exp_x, scale1, scale2;
+	float c, exp_x, s, scale1, scale2, x, y;
 	int ex_expt, half_expt;
 
 	x = crealf(z);
@@ -84,6 +84,7 @@
 	half_expt = expt - half_expt;
 	SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23);
 
-	return (CMPLXF(cosf(y) * exp_x * scale1 * scale2,
-	    sinf(y) * exp_x * scale1 * scale2));
+	sincosf(y, &s, &c);
+	return (CMPLXF(c * exp_x * scale1 * scale2,
+	    s * exp_x * scale1 * scale2));
 }