cmd/cgo: added support for GOARCH=mips64{,le}

The actual cgo is not supported for now. This is just the cgo command.

Change-Id: I25625100ee552971f47e681b7d613cba16a2132f
Reviewed-on: https://go-review.googlesource.com/14446Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

src/cmd/cgo/main.go

@@ -134,25 +134,29 @@ func usage() {
 }
 
 var ptrSizeMap = map[string]int64{
-	"386":     4,
-	"amd64":   8,
-	"arm":     4,
-	"arm64":   8,
-	"ppc64":   8,
-	"ppc64le": 8,
-	"s390":    4,
-	"s390x":   8,
+	"386":      4,
+	"amd64":    8,
+	"arm":      4,
+	"arm64":    8,
+	"mips64":   8,
+	"mips64le": 8,
+	"ppc64":    8,
+	"ppc64le":  8,
+	"s390":     4,
+	"s390x":    8,
 }
 
 var intSizeMap = map[string]int64{
-	"386":     4,
-	"amd64":   8,
-	"arm":     4,
-	"arm64":   8,
-	"ppc64":   8,
-	"ppc64le": 8,
-	"s390":    4,
-	"s390x":   4,
+	"386":      4,
+	"amd64":    8,
+	"arm":      4,
+	"arm64":    8,
+	"mips64":   8,
+	"mips64le": 8,
+	"ppc64":    8,
+	"ppc64le":  8,
+	"s390":     4,
+	"s390x":    4,
 }
 
 var cPrefix string