Update GTM and enable -Wundef and strict C++11 flags.



git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1283 4c0a9323-5329-0410-9bdc-e9ce6186880e
Initialize file descriptors to -1, not 0, in MachoWalker.

R=ivan.penkov@gmail.com

Review URL: https://breakpad.appspot.com/1174002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1284 4c0a9323-5329-0410-9bdc-e9ce6186880e