Update libm to the upstream head (2014.03.13)

The most relevant changes are the ones in s_erff.c which should improve
the overall speed of exececution and the maximum error in ULP.

Change-Id: I7bd867f902db418db67f02cd58578624357b1ee8
diff --git a/libm/upstream-freebsd/lib/msun/src/s_fmal.c b/libm/upstream-freebsd/lib/msun/src/s_fmal.c
index 9271901..d435f4f 100644
--- a/libm/upstream-freebsd/lib/msun/src/s_fmal.c
+++ b/libm/upstream-freebsd/lib/msun/src/s_fmal.c
@@ -113,7 +113,7 @@
 	if (sum.lo != 0) {
 		u.e = sum.hi;
 		bits_lost = -u.bits.exp - scale + 1;
-		if (bits_lost != 1 ^ (int)(u.bits.manl & 1))
+		if ((bits_lost != 1) ^ (int)(u.bits.manl & 1))
 			sum.hi = nextafterl(sum.hi, INFINITY * sum.lo);
 	}
 	return (ldexp(sum.hi, scale));