Add unit tests for overlapping functions and externs.
Add unit tests for overlapping functions and externs.

R=mark@chromium.org

Review URL: https://breakpad.appspot.com/3774002

git-svn-id: 7939527bf0a06ad24ad020f729d5600cb42ed5d7@1424 4c0a9323-5329-0410-9bdc-e9ce6186880e

bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad