build: mv cmd/vendor cmd/internal/unvendor

And update two imports in cmd/internal/objfile/disasm.go.
This makes GO15VENDOREXPERIMENT=0 ./make.bash work.
For Go 1.7 we will move it back.

Fixes #14236.

Change-Id: I429c9af4baff8496f83d113b1b03b90e309f4f48
Reviewed-on: https://go-review.googlesource.com/19384Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

misc/nacl/testzip.proto

@@ -27,15 +27,7 @@ go	src=..
 			internal
 				objfile
 					objfile.go
-			gofmt
-				gofmt.go
-				gofmt_test.go
-				testdata
-					+
-			newlink
-				testdata
-					+
-			vendor
+				unvendor
 					golang.org
 							x
 								arch
@@ -47,6 +39,14 @@ go	src=..
 										x86asm
 											testdata
 													+
+			gofmt
+				gofmt.go
+				gofmt_test.go
+				testdata
+					+
+			newlink
+				testdata
+					+
 		archive
 			tar
 				testdata

src/cmd/internal/objfile/disasm.go

@@ -15,8 +15,8 @@ import (
 	"strings"
 	"text/tabwriter"
 
-	"golang.org/x/arch/arm/armasm"
-	"golang.org/x/arch/x86/x86asm"
+	"cmd/internal/unvendor/golang.org/x/arch/arm/armasm"
+	"cmd/internal/unvendor/golang.org/x/arch/x86/x86asm"
 )
 
 // Disasm is a disassembler for a given File.