[3.12] gh-128605: Add branch protections for x86_64 in asm_trampolineS (#128606)...

[3.12] gh-128605: Add branch protections for x86_64 in asm_trampolineS (#128606) (#135094)

[3.12] gh-128605: Add branch protections for x86_64 in asm_trampoline.S (#128606)

Apply Intel Control-flow Technology for x86-64 on asm_trampoline.S.

Required for mitigation against return-oriented programming (ROP)
and Call or Jump Oriented Programming (COP/JOP) attacks.

Manual application is required for the assembly files.

See also: https://sourceware.org/annobin/annobin.html/Test-cf-protection.html