cmd/internal/gc: make Node.Hasbreak a bool

Node.Hasbreak was treated like a bool, so declare it as bool.

Change-Id: Ied238356dce4da896834bd1412cc21ea56d35e1d
Reviewed-on: https://go-review.googlesource.com/6807
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/internal/gc/syntax.go

@@ -55,7 +55,7 @@ type Node struct {
 	Wrapper        uint8 // is method wrapper (for func)
 	Reslice        uint8 // this is a reslice x = x[0:y] or x = append(x, ...)
 	Likely         int8  // likeliness of if statement
-	Hasbreak       uint8 // has break statement
+	Hasbreak       bool  // has break statement
 	Needzero       bool  // if it contains pointers, needs to be zeroed on function entry
 	Needctxt       bool  // function uses context register (has closure variables)
 	Esc            uint  // EscXXX