- It seems that needing to link M objects with `cc` on ARM versus
  standard `ld` is no longer needed based on manual testing on an ARM6
  system.
- Standardize on `ld.gold` (not ld, for Alpine's sake, per commit
  65751cd2)
- Check for `ld.gold` in `ydbinstall`
- Check result of ld operation, so we don't have a repeat of the issue
  in #1043: the command failed (it was not found on the system), but we
  never checked what the status was.

Tested using the sudo suite on x64/ARM7 systems; and tested that
Dockerfiles build properly on x64/ARM7 and contain `libyottadbutil.so`
file.