Hardcode the compiler version in the build key once and for all
    
    * Wed Aug 19 2020 Kevin Kofler <Kevin@tigcc.ticalc.org> - 4.8.7-57
    - Hardcode the compiler version in the build key once and for all
    
    It does not make sense to have to mess with the build key again and
    again at each GCC major version. GCC major versions no longer carry any
    ABI meaning as in the days of GCC 2.95 vs. 3.0. And nobody really uses a
    GCC older than 4.0 anymore. So we just hardcode the compiler version in
    the build key to "4". See also my corresponding Qt 3 patch from January
    2019.