cmd/internal/gc: convert yet more Node fields to bools

Convert Embedded, Method, and Colas to bools.

I believe that this is the last of the Node fields
that can be trivially converted to bools.

No functional changes. Passes toolstash -cmp.

Change-Id: I81962ee47866596341fc60d24d6959c20cd7fc1c
Reviewed-on: https://go-review.googlesource.com/8440
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/8g/ggen.go b/src/cmd/8g/ggen.go
index a4a373c..115c962 100644
--- a/src/cmd/8g/ggen.go
+++ b/src/cmd/8g/ggen.go
@@ -637,7 +637,7 @@
 		// binary
 		if nl.Ullman >= nr.Ullman {
 			gc.Cgen(nl, &f0)
-			if nr.Addable != 0 {
+			if nr.Addable {
 				gins(foptoas(int(n.Op), n.Type, 0), nr, &f0)
 			} else {
 				gc.Cgen(nr, &f0)
@@ -645,7 +645,7 @@
 			}
 		} else {
 			gc.Cgen(nr, &f0)
-			if nl.Addable != 0 {
+			if nl.Addable {
 				gins(foptoas(int(n.Op), n.Type, Frev), nl, &f0)
 			} else {
 				gc.Cgen(nl, &f0)
@@ -762,14 +762,14 @@
 	var n2 gc.Node
 	var ax gc.Node
 	if !gc.Thearch.Use387 {
-		if nl.Addable == 0 {
+		if !nl.Addable {
 			var n1 gc.Node
 			gc.Tempname(&n1, nl.Type)
 			gc.Cgen(nl, &n1)
 			nl = &n1
 		}
 
-		if nr.Addable == 0 {
+		if !nr.Addable {
 			var tmp gc.Node
 			gc.Tempname(&tmp, nr.Type)
 			gc.Cgen(nr, &tmp)