Make BuildRequires independent of the environment
    
    The spec file had
      %if %{defined rhel} && 0%{?rhel} < 10
      %define gobuild(o:) ...
      %endif
      ...
      %if !%{defined gobuild}
      BuildRequires: go-rpm-macros
      %endif
    
    The intent apparently was to use BR:go-rpm-macros where available, and define
    %gobuild as a fallback where they are not available. This was unreliable,
    because the package may have been installed already, and then %gobuild would be
    defined when the srpm was being built, and then the srpm would NOT have the BR.
    
    Instead, use the same condition to wrap the definition of %gobuild and the BR
    lines to that the BR is always emitted when appropriate.