MFC r332270, r332272, r332275, r332413: nop

r332270:
loader: include efi.4th only if we do have uefi

Also simplify efi.4th.

r332272:
loader: 332270 did use wrong path for efi.4th

The correct path is still /boot/efi.4th

r332275:
loader: 332270 did left out stand/i386/loader/loader.rc

we have 2 instances of loader.rc...

r332413:
Revert r332275, r332272, r332270

There's problems with them. The order of efi stuff isn't quite right,
and there's various problems. Revert until thos problems can be fixed.