Added gcc 64-bit for rake

This adds a gcc_64.yml to targets/ so that rake in extras/fixture no longer fails on 64-bit systems with no 32-bit support. You have to change the rakefile to use gcc_64.yml for that.

For some reason, the rake command deleted two files in the extras/fixtures/build directory. Not sure what they were here for. If these are autogenerated/autodeleted files, they probably should not be in the rep?