Add Linux 32-bit versions of Ninja

ninja

 #!/bin/bash
 
 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 OS="$(uname -s)"
 THIS_DIR="$(dirname "${0}")"
 
 if [ "${OS}" = "Linux" ]; then
-  exec "${THIS_DIR}/ninja-linux64" "$@"
+  machine=$(getconf LONG_BIT)
+  if [[ "$machine" = "64" ]]; then
+    exec "${THIS_DIR}/ninja-linux64" "$@"
+  elif [[ "$machine" = "32" ]]; then
+    exec "${THIS_DIR}/ninja-linux32" "$@"
+  else
+    echo Unknown architecture \($machine\) -- unable to run ninja.
+    exit 1
+  fi
 elif [ "${OS}" = "Darwin" ]; then
   exec "${THIS_DIR}/ninja-mac" "$@"
 elif [[ ${OS} == CYGWIN* ]]; then
   exec cmd.exe /c `cygpath -t windows $0`.exe "$@"
 elif [[ ${OS} == MINGW32* ]]; then
   cmd.exe //c $0.exe "$@"
 else
   echo "Unsupported OS ${OS}"
   exit 1
 fi