[MC,x86-32] Remove a gold<2.34 workaround

This workaround appears to apply with gold<2.34 -O2/-O3 (linker -O2, not
compiler driver -O2). This used to be more visible as we used -Wl,-O3 in
CMake, but the option is generally not recommended and has been removed
by d63016a8 (Dec 2021).

This finishes a workaround removal work started by D64327 (2019).

Link: https://github.com/llvm/llvm-project/issues/45269