stand: Stop building in fat, ext2fs, gzip and bzip to BIOS /boot/loader

[imp]

Summary

This saves space to allow pxeboot to work again. Users desiring these
features can turn them on for their custom build. While these are useful
for some specialized applications, they aren't needed to boot the
typical system, and we're low on space.

text    data     bss      dec       hex   filename

Before: 465866 20740 31612 518218 0x7e84a loader_lua.bin
After: 441535 17484 31092 490111 0x77a7f loader_lua.bin

Savings: 28,107 bytes

Sponsored by: Netflix

Test Plan

This is a stop-gap, but a super-easy one to do.

I'm ruing the day we have to enforce a freeze on new features/compression/crypto in ZFS so things will still fit.

[kevans]

Good selection

[emaste]

stand/i386/loader/Makefile

10–11

I think this is in somewhat wide use?

[imp]

stand/i386/loader/Makefile

10–11

They will need to build custom. I could add MK_LOADER_BIOS_xxx maybe

[jo_bruelltuete.com]

stand/i386/loader/Makefile

10–11

I just got bitten in the butt by this with upgrading from 13.3 to 13.4.
Would have been good to mention this in UPDATING or release notes.

[imp]

stand/i386/loader/Makefile

10–11

Yes. It would have been nice, but I didn't think of it in time for either. And I didn't appreciate that people would care until they started getting bitten by it. And after I saw who was affected, I knew I should have done more, but all I could do is fix it like this after the fact. I'm sorry that this cause you grief, and vastly underestimated its popularity.