[llvm-mc] - Produce R_X86_64_PLT32 relocation for branches with JCC opcodes too.

The idea is to produce R_X86_64_PLT32 instead of
R_X86_64_PC32 for branches.

It fixes https://bugs.llvm.org/show_bug.cgi?id=44397.

This patch teaches MC to do that for JCC (jump if condition is met)
instructions. The new behavior matches modern GNU as.
It is similar to D43383, which did the same for "call/jmp foo",
but missed JCC cases.

Differential revision: https://reviews.llvm.org/D72831