[x86] regenerate checks with update_llc_test_checks.py

The dream of a unified check-line auto-generator for all phases of compilation is dead.
The llc script has already diverged to be better at its goal, so having 2 scripts that
do almost the same thing is just causing confusion for newcomers. I plan to fix up more
x86 tests in a next commit. We can rip out the llc ability in update_test_checks.py after
that. 

llvm-svn: 305202