os:windows but nim puts 'lpthread'

[janAkali]

"-lpthread" flag is added by the default `nim.cfg`:
    
    
    # Configuration for the GNU C/C++ compiler:
    @if windows:
      ...
      @if gcc:
        gcc.options.linker %= "-Wl,-Bstatic -lpthread"
      @end
      ...
    @end
    
    
    Run

To override it - create a local `nim.cfg` in project directory with this 
content:
    
    
    @if windows:
      @if gcc:
        gcc.options.linker = "-Wl,-Bstatic"
      @end
    @end
    
    
    Run