cmd/compile: added support for mips64{,le}

It is based on ppc64 compiler.

Change-Id: I15a101df05f2919ba5292136957ba0009227d067
Reviewed-on: https://go-review.googlesource.com/14445
Reviewed-by: Minux Ma <minux@golang.org>
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index a2bdbdc..9051be0 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -3290,7 +3290,7 @@
 }
 
 func walkrotate(np **Node) {
-	if Thearch.Thechar == '7' || Thearch.Thechar == '9' {
+	if Thearch.Thechar == '0' || Thearch.Thechar == '7' || Thearch.Thechar == '9' {
 		return
 	}
 
@@ -3418,7 +3418,7 @@
 	// if >= 0, nr is 1<<pow // 1 if nr is negative.
 
 	// TODO(minux)
-	if Thearch.Thechar == '7' || Thearch.Thechar == '9' {
+	if Thearch.Thechar == '0' || Thearch.Thechar == '7' || Thearch.Thechar == '9' {
 		return
 	}