cmd/cgo: handle another Clang DWARF quirk

Without the fix:

    $ CC=clang-3.5 ./test.bash
    misc/cgo/errors/test.bash: BUG: expected error output to contain "C.ushort" but saw:
    # command-line-arguments
    ./issue13129.go:13: cannot use int(0) (type int) as type C.unsignedshort in assignment

Fixes #13129.

Change-Id: I2c019d2d000f5bfa3e33c477e533aff97031a84f
Reviewed-on: https://go-review.googlesource.com/17207
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

misc/cgo/errors/issue13129.go

+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// issue 13129: used to output error about C.unsignedshort with CC=clang
+
+package main
+
+import "C"
+
+func main() {
+	var x C.ushort
+	x = int(0) // ERROR HERE
+}

misc/cgo/errors/test.bash

@@ -11,6 +11,12 @@ check() {
 		echo 1>&2 misc/cgo/errors/test.bash: BUG: cannot find ERROR HERE in $file
 		exit 1
 	fi
+	expect $file $file:$line:
+}
+
+expect() {
+	file=$1
+	error=$2
 	if go build $file >errs 2>&1; then
 		echo 1>&2 misc/cgo/errors/test.bash: BUG: expected cgo to fail but it succeeded
 		exit 1
@@ -19,8 +25,8 @@ check() {
 		echo 1>&2 misc/cgo/errors/test.bash: BUG: expected error output but saw none
 		exit 1
 	fi
-	if ! fgrep $file:$line: errs >/dev/null 2>&1; then
-		echo 1>&2 misc/cgo/errors/test.bash: BUG: expected error on line $line but saw:
+	if ! fgrep $error errs >/dev/null 2>&1; then
+		echo 1>&2 misc/cgo/errors/test.bash: BUG: expected error output to contain \"$error\" but saw:
 		cat 1>&2 errs
 		exit 1
 	fi
@@ -33,6 +39,7 @@ check issue7757.go
 check issue8442.go
 check issue11097a.go
 check issue11097b.go
+expect issue13129.go C.ushort
 
 if ! go run ptr.go; then
 	exit 1

src/cmd/cgo/gcc.go

@@ -1314,6 +1314,7 @@ var dwarfToName = map[string]string{
 	"long unsigned int":      "ulong",
 	"unsigned int":           "uint",
 	"short unsigned int":     "ushort",
+	"unsigned short":         "ushort", // Used by Clang; issue 13129.
 	"short int":              "short",
 	"long long int":          "longlong",
 	"long long unsigned int": "ulonglong",