Sync libm with upstream.

Change-Id: I8ac8ee52122ee19a2e423c3211092023cb4896eb
diff --git a/libm/upstream-freebsd/lib/msun/src/e_pow.c b/libm/upstream-freebsd/lib/msun/src/e_pow.c
index 7607a4a..d54af9d 100644
--- a/libm/upstream-freebsd/lib/msun/src/e_pow.c
+++ b/libm/upstream-freebsd/lib/msun/src/e_pow.c
@@ -19,20 +19,20 @@
  *	1. Compute and return log2(x) in two pieces:
  *		log2(x) = w1 + w2,
  *	   where w1 has 53-24 = 29 bit trailing zeros.
- *	2. Perform y*log2(x) = n+y' by simulating muti-precision 
+ *	2. Perform y*log2(x) = n+y' by simulating multi-precision 
  *	   arithmetic, where |y'|<=0.5.
  *	3. Return x**y = 2**n*exp(y'*log2)
  *
  * Special cases:
  *	1.  (anything) ** 0  is 1
  *	2.  (anything) ** 1  is itself
- *	3.  (anything) ** NAN is NAN
+ *	3.  (anything) ** NAN is NAN except 1 ** NAN = 1
  *	4.  NAN ** (anything except 0) is NAN
  *	5.  +-(|x| > 1) **  +INF is +INF
  *	6.  +-(|x| > 1) **  -INF is +0
  *	7.  +-(|x| < 1) **  +INF is +0
  *	8.  +-(|x| < 1) **  -INF is +INF
- *	9.  +-1         ** +-INF is NAN
+ *	9.  +-1         ** +-INF is 1
  *	10. +0 ** (+anything except 0, NAN)               is +0
  *	11. -0 ** (+anything except 0, NAN, odd integer)  is +0
  *	12. +0 ** (-anything except 0, NAN)               is +INF
@@ -141,7 +141,7 @@
 	if(ly==0) { 	
 	    if (iy==0x7ff00000) {	/* y is +-inf */
 	        if(((ix-0x3ff00000)|lx)==0)
-		    return  one;	/* (-1)**+-inf is NaN */
+		    return  one;	/* (-1)**+-inf is 1 */
 	        else if (ix >= 0x3ff00000)/* (|x|>1)**+-inf = inf,0 */
 		    return (hy>=0)? y: zero;
 	        else			/* (|x|<1)**-,+inf = inf,0 */