FROMLIST: x86/boot: allow a relocatable kernel to be linked with lld

LLD by default disallows relocations in read-only segments. For a
relocatable kernel, we pass -z notext to the linker to explicitly
allow relocations. This behavior is the default for BFD.

Link: https://github.com/ClangBuiltLinux/linux/issues/579


Signed-off-by: Dmitry Golovin <dima@golovin.in>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
[adelva: ndesaulniers notes this is a simpler alternative to the
         upstream fix that is hard to backport to 5.4 due to many
         x86 assembler changes]
Link: https://lore.kernel.org/lkml/20200501084215.242-1-dima@golovin.in/


Bug: 65987925
Signed-off-by: Alistair Delva <adelva@google.com>
Change-Id: Ie0085504ff58e468ad5b3f71014b58151b2f2f2d