Minor fix in profiling script, part 2

tools-webrtc/android/profiling/perf_setup.sh

 #!/bin/bash
 
 # Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 #
@@ skipping 180 matching lines @@
   printf " perf_report_graph\n"
   printf " perf_report_graph_callee\n"
   printf " perf_update\n"
   printf " perf_clean\n"
   printf " flame_graph\n"
   printf " plot_flame_graph\n"
 }
 
 function cleanup() {
   unset -f main
-  unset BUILD_DIR
 }
 
 # -----------------------------------------------------------------------------
 # Main methods to be used after sourcing the main script.
 # -----------------------------------------------------------------------------
 
 # Call this method after the application as been rebuilt and installed on the
 # device to ensure that symbols are up-to-date.
 function perf_update() {
   copy_native_shared_library_to_symbol_cache
@@ skipping 249 matching lines @@
 
   cleanup
 
   return 0
 }
 
 # Only call main() if proper input parameter has been provided.
 if is_set $BUILD_DIR; then
   main "$@"
 fi