In an ideal world everyone would just install `gdb-multiarch` and be
happy. However, some MCUs need magic GDB versions sprinkled with
unicorn-stardust-Espressif-patches...
Since there is little reason to have `$(target)-gdb` installed in
addition to `gdb-multiarch` if `gdb-multiarch` would work fine, let's
assume the user wants to use `$(target)-gdb` when present over
`gdb-multiarch`.
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
