cmd/compile: switch Eqtype and (*Type).Compare to use recvParamsResults

Change-Id: I5365b94b815bfb4795db643415c2df51fc815ea1
Reviewed-on: https://go-review.googlesource.com/20459
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dave Cheney <dave@cheney.net>

src/cmd/compile/internal/gc/subr.go

@@ -767,7 +767,7 @@ func eqtype1(t1, t2 *Type, assumedEqual map[typePair]struct{}) bool {
 
 		// Loop over structs: receiver, in, out.
 	case TFUNC:
-		for _, f := range [...]func(*Type) *Type{(*Type).Recv, (*Type).Results, (*Type).Params} {
+		for _, f := range recvParamsResults {
 			// Loop over fields in structs, ignoring argument names.
 			ta, ia := IterFields(f(t1))
 			tb, ib := IterFields(f(t2))

src/cmd/compile/internal/gc/type.go

@@ -423,7 +423,7 @@ func (t *Type) cmp(x *Type) ssa.Cmp {
 		return ssa.CMPeq
 
 	case TFUNC:
-		for _, f := range [...]func(*Type) *Type{(*Type).Recv, (*Type).Results, (*Type).Params} {
+		for _, f := range recvParamsResults {
 			// Loop over fields in structs, ignoring argument names.
 			ta, ia := IterFields(f(t))
 			tb, ib := IterFields(f(x))