Sync upstream FreeBSD libm.

Test: treehugger
Change-Id: I583a3e93821d512c975db34fc1610ffd22445d58
diff --git a/libm/upstream-freebsd/lib/msun/src/s_erf.c b/libm/upstream-freebsd/lib/msun/src/s_erf.c
index 5f22847..ab2dc19 100644
--- a/libm/upstream-freebsd/lib/msun/src/s_erf.c
+++ b/libm/upstream-freebsd/lib/msun/src/s_erf.c
@@ -238,7 +238,7 @@
 	}
 	z  = x;
 	SET_LOW_WORD(z,0);
-	r  =  __ieee754_exp(-z*z-0.5625)*__ieee754_exp((z-x)*(z+x)+R/S);
+	r  =  exp(-z*z-0.5625)*exp((z-x)*(z+x)+R/S);
 	if(hx>=0) return one-r/x; else return  r/x-one;
 }
 
@@ -297,7 +297,7 @@
 	    }
 	    z  = x;
 	    SET_LOW_WORD(z,0);
-	    r  =  __ieee754_exp(-z*z-0.5625)*__ieee754_exp((z-x)*(z+x)+R/S);
+	    r  =  exp(-z*z-0.5625)*exp((z-x)*(z+x)+R/S);
 	    if(hx>0) return r/x; else return two-r/x;
 	} else {
 	    if(hx>0) return tiny*tiny; else return two-tiny;