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/internal/gc/closure.go b/src/cmd/internal/gc/closure.go
index a5364fc..62e060e 100644
--- a/src/cmd/internal/gc/closure.go
+++ b/src/cmd/internal/gc/closure.go
@@ -599,7 +599,7 @@
 	ptr := Nod(ONAME, nil, nil)
 	ptr.Sym = Lookup("rcvr")
 	ptr.Class = PAUTO
-	ptr.Addable = 1
+	ptr.Addable = true
 	ptr.Ullman = 1
 	ptr.Used = true
 	ptr.Curfn = xfunc