games/xash3d: build fails on i386

``` ===> Configuring for xash3d-hl-0.0.70bd3a2 [26/1964] CMake Deprecation Warning at CMakeLists.txt:23 (cmake_minimum_required): Compatibility with CMake < 2.8.12 will be removed from a future version of CMake. Update the VERSION argument <min> value or use a ...<max> suffix to tell CMake that the project does not need compatibility with older versions. -- The C compiler identification is Clang 11.1.0 -- The CXX compiler identification is Clang 11.1.0 -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler: /usr/ports/pobj/xash3d-hl-0.0.70bd3a2/bin/cc - skipped -- Detecting C compile features -- Detecting C compile features - done -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler: /usr/ports/pobj/xash3d-hl-0.0.70bd3a2/bin/c++ - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done CMake Error at CMakeLists.txt:65 (message): You enabled XASH_64BIT, but compiler can't create 64 bit code! ``` It seems XASH_64BIT is still getting defined even though I'm on a 32-bit platform.