Adding valgrind to .gitignore

Review URL: http://webrtc-codereview.appspot.com/289005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@1032 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/.gitignore b/.gitignore
index fa388b0..ec61a78 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,9 +46,12 @@
 /third_party/libvpx
 /third_party/llvm-build
 /third_party/protobuf
+/third_party/valgrind
 /third_party/yasm
 /tools/clang
 /tools/gyp
+/tools/python
+/tools/valgrind
 /tools/win
 /x86-generic_out/
 /xcodebuild