cygwin: cmake expression should not change for linux

+1
+1
pkgs/development/tools/build-managers/cmake/default.nix
··· 53 "--docdir=/share/doc/${name}" 54 "--mandir=/share/man" 55 ] 56 ++ optional (jsoncpp == null || stdenv.isCygwin) "--no-system-jsoncpp" 57 ++ optional useQt4 "--qt-gui" 58 ++ ["--"]
··· 53 "--docdir=/share/doc/${name}" 54 "--mandir=/share/man" 55 ] 56 + ++ optional (!stdenv.isCygwin) "--system-libs" 57 ++ optional (jsoncpp == null || stdenv.isCygwin) "--no-system-jsoncpp" 58 ++ optional useQt4 "--qt-gui" 59 ++ ["--"]