x86/linker: add a reloc section to ELF linker script

x86/linker: add a reloc section to ELF linker script

if the hypervisor has been built with EFI support (ie: multiboot2).
This allows to position the .reloc section correctly in the output
binary.

Note that for the ELF output format the .reloc section is moved before
.bss because the data it contains is read-only, so it belongs with the
other sections containing read-only data.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>