Daiderd Jordan 54b4000d54 csfml: mark linux only ...

While it's possible to build on darwin, we never had a successful build.

    Undefined symbols for architecture x86_64:
      "sf::microseconds(long long)", referenced from:
          _sfSleep in Sleep.cpp.o

/cc ZHF #45961

2018-09-13 23:08:49 +02:00

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default.nix

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