x86_64 builds now require -lopcodes

Recent changes to objtool that landed during the merge window require libopcodes (provided by binutils-dev) for x86_64 builds, without it objtool fails to link:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/tools/objtool?id=59953303827eceb06d486ba66cc0d71f55ded8ec