cmd/internal/gc: make Node.Isddd boolean

Convert Node.Isddd to a boolean and simplify usage.

- Node.Isddd converted to bool
- Type.Isddd converted to bool
- mkinlcall converted to take isddd as a bool
- typecheckaste converted to take isddd as a bool
- ascompatte converted to take isddd as a bool

Change-Id: I52586145619c44182bb0c2c5d80a0a3fe3e50a07
Reviewed-on: https://go-review.googlesource.com/7172
Reviewed-by: Keith Randall <khr@golang.org>
diff --git a/src/cmd/internal/gc/reflect.go b/src/cmd/internal/gc/reflect.go
index 797f62a..36aa0b6 100644
--- a/src/cmd/internal/gc/reflect.go
+++ b/src/cmd/internal/gc/reflect.go
@@ -1051,9 +1051,9 @@
 		for t1 = getthisx(t).Type; t1 != nil; t1 = t1.Down {
 			dtypesym(t1.Type)
 		}
-		isddd := 0
+		isddd := false
 		for t1 = getinargx(t).Type; t1 != nil; t1 = t1.Down {
-			isddd = int(t1.Isddd)
+			isddd = t1.Isddd
 			dtypesym(t1.Type)
 		}
 
@@ -1063,7 +1063,7 @@
 
 		ot = dcommontype(s, ot, t)
 		xt = ot - 3*Widthptr
-		ot = duint8(s, ot, uint8(isddd))
+		ot = duint8(s, ot, uint8(bool2int(isddd)))
 
 		// two slice headers: in and out.
 		ot = int(Rnd(int64(ot), int64(Widthptr)))