FROMLIST: x86/boot: Check that there are no run-time relocations

Add a linker script check that there are no run-time relocations, and
remove the old one that tries to check via looking for specially-named
sections in the object files.

Drop the tests for -fPIE compiler option and -pie linker option, as they
are available in all supported gcc and binutils versions (as well as
clang and lld).

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Fangrui Song <maskray@google.com>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/lkml/20200629140928.858507-8-nivedita@alum.mit.edu


Bug: 167402429
Signed-off-by: Alistair Delva <adelva@google.com>
Change-Id: I13a1e5a3292e3b4fb054e1489f269964a31428e9