build: also check for empty .bss.* in .o -> .init.o conversion

build: also check for empty .bss.* in .o -> .init.o conversion

We're gaining such sections, and like .text.* and .data.* they shouldn't
be present in objects subject to automatic to-init conversion. Oddly
enough for quite some time we did have an instance breaking this rule,
which gets fixed at this occasion, by breaking out the EFI boot
allocator functions into its own translation unit.

Fixes: c5b9805bc1f7 ("efi: create new early memory allocator")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Julien Grall <jgrall@amazon.com>