Fix typo to make clang plugin tests work on linux.

tools/clang/plugins/tests/test.sh

 #!/bin/bash
 #
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # Hacky, primitive testing: This runs the style plugin for a set of input files
 # and compares the output with golden result files.
 
 E_BADARGS=65
@@ skipping 31 matching lines @@
 
 # Validate input to the script.
 if [[ -z "${1}" ]]; then
   usage
   exit ${E_BADARGS}
 elif [[ ! -d "${1}" ]]; then
   echo "${1} is not a directory."
   usage
   exit ${E_BADARGS}
 else
-  export CLANG_DIR="$(PWD)/${1}"
+  export CLANG_DIR="${PWD}/${1}"
   echo "Using clang directory ${CLANG_DIR}..."
 
   # The golden files assume that the cwd is this directory. To make the script
   # work no matter what the cwd is, explicitly cd to there.
   cd "$(dirname "${0}")"
 
   if [ "$(uname -s)" = "Linux" ]; then
     export LIB=so
   elif [ "$(uname -s)" = "Darwin" ]; then
     export LIB=dylib
   fi
 fi
 
 for input in *.cpp; do
   do_testcase "${input}" "${input%cpp}txt"
 done
 
 if [[ "${failed_any_test}" ]]; then
   exit ${E_FAILEDTEST}
 fi