Intel Control-flow Enforcement Technology (CET) provides new instructions `endbr32/64` for the indirect branch control. They are NOPs on i686 and new targets. We need to check for that in case it crashes on older targets. PR: 264497 Obtained from: LLVM commit 52516782972730ff065a34123a9d8876da08c254
(I think this will introduce a (trivially resolved) conflict on the next import.)