Add initial experimental LTO support

This will not succeed in compiling on all target and compiler
combinations but at least gets the ball rolling. The change is not
invasive.

Some notes:
- GCC has issues with LTO on ARM
- Clang uses LLD automatically on some arch
- Clang with LTO fails on x86 as it forwards the linking to GCC for some
  reason
- SMM building succeeds but the binary is empty

Change-Id: Ieb9204777fd349542744a8946e2207731c37969c
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84003
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>

0 files changed, 0 insertions, 0 deletions