Checking in checkbin.py, a tool to make sure our Windows binaries were built correctly.

It looks for binaries built with /NXCOMPAT and /DYNAMICBASE, two important security features for Windows binaries.

BUG=25952
TEST=try running it on the output of /src/chrome/Debug

Review URL: http://codereview.chromium.org/338052

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@30304 0039d316-1c4b-4281-b951-d872f2087c98