cmd/compile: refactor order.go into methods

No functional changes, just changing all the orderfoo functions
into (*Order).foo methods.

Passes toolstash-check.

Change-Id: Ib9833daa98aff3c645ce56794a414f8472689152
Reviewed-on: https://go-review.googlesource.com/98617
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

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

@@ -760,7 +760,7 @@ func fixedlit(ctxt initContext, kind initKind, n *Node, var_ *Node, init *Nodes)
 		case initKindStatic:
 			genAsStatic(a)
 		case initKindDynamic, initKindLocalCode:
-			a = orderstmtinplace(a)
+			a = orderStmtInPlace(a)
 			a = walkstmt(a)
 			init.Append(a)
 		default:
@@ -911,7 +911,7 @@ func slicelit(ctxt initContext, n *Node, var_ *Node, init *Nodes) {
 		a = nod(OAS, a, value)
 
 		a = typecheck(a, Etop)
-		a = orderstmtinplace(a)
+		a = orderStmtInPlace(a)
 		a = walkstmt(a)
 		init.Append(a)
 	}
@@ -920,7 +920,7 @@ func slicelit(ctxt initContext, n *Node, var_ *Node, init *Nodes) {
 	a = nod(OAS, var_, nod(OSLICE, vauto, nil))
 
 	a = typecheck(a, Etop)
-	a = orderstmtinplace(a)
+	a = orderStmtInPlace(a)
 	a = walkstmt(a)
 	init.Append(a)
 }