[dev.power64] cmd/cgo: add {ppc,power}64{,le} to pointer and int size maps

LGTM=rsc
R=rsc, iant, dave
CC=golang-codereviews
https://golang.org/cl/119640043

src/cmd/cgo/main.go

@@ -133,12 +133,20 @@ var ptrSizeMap = map[string]int64{
 	"386":       4,
 	"amd64":     8,
 	"arm":       4,
+	"ppc64":     8,
+	"ppc64le":   8,
+	"power64":   8,
+	"power64le": 8,
 }
 
 var intSizeMap = map[string]int64{
 	"386":       4,
 	"amd64":     8,
 	"arm":       4,
+	"ppc64":     8,
+	"ppc64le":   8,
+	"power64":   8,
+	"power64le": 8,
 }
 
 var cPrefix string