cmd/vendor/golang.org/x/arch: import latest (Aug 18 2017 ffd22fb365cd)

Fixes #21486.

Change-Id: I01794f008404f0e2d8a1408309ae6055513c5b49
Reviewed-on: https://go-review.googlesource.com/57030
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/vendor/golang.org/x/arch/arm64/arm64asm/ext_test.go

@@ -503,7 +503,7 @@ func JSONCases(t *testing.T) func(func([]byte)) {
 	return func(try func([]byte)) {
 		data, err := ioutil.ReadFile("inst.json")
 		if err != nil {
-			log.Fatal(err)
+			t.Fatal(err)
 		}
 		var insts []InstJson
 		var instsN []InstJson
@@ -513,7 +513,7 @@ func JSONCases(t *testing.T) func(func([]byte)) {
 			N = 16
 		}
 		if err := json.Unmarshal(data, &insts); err != nil {
-			log.Fatal(err)
+			t.Fatal(err)
 		}
 		// Append instructions to get more test cases.
 		for i := 0; i < N; {

src/cmd/vendor/golang.org/x/arch/arm64/arm64asm/objdumpext_test.go

@@ -27,27 +27,19 @@ func testObjdumpARM64(t *testing.T, generate func(func([]byte))) {
 }
 
 func testObjdumpArch(t *testing.T, generate func(func([]byte)), arch Mode) {
-	if _, err := os.Stat(objdumpPath); err != nil {
-		t.Skip(err)
-	}
-	// Check objdump can disassemble elf64-aarch64.
-	if test := objdumpinfo(); test == false {
-		t.Skip("Skip the test if installed objdump doesn't support aarch64 elf format")
-	}
+	checkObjdumpAarch64(t)
 	testExtDis(t, "gnu", arch, objdump, generate, allowedMismatchObjdump)
 	testExtDis(t, "plan9", arch, objdump, generate, allowedMismatchObjdump)
 }
 
-func objdumpinfo() bool {
-	var i = []byte("aarch64")
+func checkObjdumpAarch64(t *testing.T) {
 	out, err := exec.Command(objdumpPath, "-i").Output()
 	if err != nil {
-		log.Fatal(err)
+		t.Skip("cannot run objdump: %v\n%s", err, out)
 	}
-	if bytes.Contains(out, i) {
-		return true
+	if !strings.Contains(string(out), "aarch64") {
+		t.Skip("objdump does not have aarch64 support")
 	}
-	return false
 }
 
 func objdump(ext *ExtDis) error {