math: update definition of NaN in assembly language files

R=rsc, minux.ma, golang-dev, nigeltao
CC=golang-dev
https://golang.org/cl/6461047

src/pkg/math/dim_amd64.s

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #define PosInf 0x7FF0000000000000
-#define NaN    0x7FF0000000000001
+#define NaN    0x7FF8000000000001
 #define NegInf 0xFFF0000000000000
 
 // func Dim(x, y float64) float64

src/pkg/math/hypot_386.s

@@ -48,7 +48,7 @@ not_finite:
 	ANDL    $0x7fffffff, AX
 	CMPL    AX, $0x7ff00000
 	JEQ     is_inf
-	MOVL    $0x7ff00000, rh+20(FP)  // return NaN = 0x7FF0000000000001
+	MOVL    $0x7ff80000, rh+20(FP)  // return NaN = 0x7FF8000000000001
 	MOVL    $0x00000001, rl+16(FP)
 	RET
 is_inf:

src/pkg/math/hypot_amd64.s

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#define PosInf 0x7ff0000000000000
-#define NaN 0x7FF0000000000001
+#define PosInf 0x7FF0000000000000
+#define NaN 0x7FF8000000000001
 
 // func Hypot(x, y float64) float64
 TEXT ·Hypot(SB),7,$0

src/pkg/math/log_amd64.s

@@ -12,7 +12,7 @@
 #define L5     1.818357216161805012e-01   // 0x3FC7466496CB03DE
 #define L6     1.531383769920937332e-01   // 0x3FC39A09D078C69F
 #define L7     1.479819860511658591e-01   // 0x3FC2F112DF3E5244
-#define NaN    0x7FF0000000000001
+#define NaN    0x7FF8000000000001
 #define NegInf 0xFFF0000000000000
 #define PosInf 0x7FF0000000000000
 

src/pkg/math/sincos_amd64.s

@@ -19,7 +19,7 @@
 
 #define PosOne 0x3FF0000000000000
 #define PosInf 0x7FF0000000000000
-#define NaN    0x7FF0000000000001
+#define NaN    0x7FF8000000000001
 #define PI4A 0.7853981554508209228515625 // pi/4 split into three parts
 #define PI4B 0.794662735614792836713604629039764404296875e-8
 #define PI4C 0.306161699786838294306516483068750264552437361480769e-16