FROMLIST: scripts/mod: disable LTO for empty.c

With CONFIG_LTO_CLANG, clang generates LLVM IR instead of ELF object
files. As empty.o is used for probing target properties, disable LTO
for it to produce an object file instead.

Bug: 62093296
Bug: 67506682
Change-Id: I0c7ac7ee0134465cac4a8c3a9c7e8b6347076a2b
(am from https://patchwork.kernel.org/patch/10060317/

)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>