Coverity project for GRUB

[Andrei Borzenkov]

I set up Coverity project:
https://scan.coverity.com/projects/3406?tab=overview

There are quite a few of false positives caused by
grub_fshelp_find_file, but otherwise it does find real bugs. There are
slightly above 300 incidents in total.

I myself build it for i386-pc; if you have possibilities to submit
builds for other platforms would be great. We probably need some
agreement on how to name build versions.