This CL introduces a new directory for WebRTC utility scripts for Valgrind: tools/valgrind-webrtc

To be able to re-use as much as possible from Chromium's scripts, I've created two customized scripts for running tests:
- webrtc_tests.py: a customized version of chrome_tests.py with WebRTC tests instead.
- webrtc_tests.sh: a customized version of the chrome_tests.sh wrapper script, to launch the above script.

The webrtc_tests.sh script is setting up PYTHONPATH so that tools/valgrind is available for the webrtc_tests.py script.
The webrtc_tests.py script inherits the chrome_tests.py script as much as possible, to minimize maintenance and maximize readability.
Having this mirrored setup of directories, allows us to use the same directory hierarchy for suppression files too. This CL only adds suppression files for memcheck, but we can add files for tsan later easily.

The suppression file is currently empty for Linux. For Mac I copied all the Chromium third-party suppressions. We will need a lot more added for Mac before Valgrind runs becomes usable for that platform.
The platform specific naming of the suppression files are handled automatically when webrtc_tests.sh  is used to launch the tests.

Example:
Plain memcheck (default tool): tools/valgrind-webrtc/webrtc_tests.sh -t system_wrappers
Run ThreadSanitizer: tools/valgrind-webrtc/webrtc_tests.sh  --tool=tsan -t system_wrappers

Previously mentioned AddressSanitizer requires additional scripts to be added and it not covered in this CL.

BUG=
TEST=

Review URL: http://webrtc-codereview.appspot.com/322010

git-svn-id: http://webrtc.googlecode.com/svn/trunk@1240 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/.gitignore b/.gitignore
index 1896c63..e011861 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,6 +36,7 @@
 /resources
 /src/supplement.gypi
 /testing
+/third_party/asan
 /third_party/cygwin
 /third_party/expat
 /third_party/google-gflags/src