Tweak gitignore rules for third_party/mozc

This is to make 'git clean' a no-op.

BUG=

Review URL: https://chromiumcodereview.appspot.com/10837024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149211 0039d316-1c4b-4281-b951-d872f2087c98

.gitignore

@@ -175,8 +175,7 @@ v8.log
 /third_party/lss
 /third_party/mingw-w64
 /third_party/mkl
-/third_party/mozc/chrome/chromeos/renderer
-/third_party/mozc/session
+/third_party/mozc
 /third_party/nacl_sdk_binaries/
 /third_party/nss
 /third_party/openssl