Quake4 1.2.1 for GNULinux x86

Description
This update is fully compatible with other versions of Quake4 1.2. The main reason for this release is the addition of SMP renderer acceleration to the Linux version. Same rules apply for Linux SMP as they do on Windows. Depending on your system ( CPU limited, GPU limited, processor cache sizes.. ), this may or may not improve performance.

The SMP binary requires a modified version of the SDL library, which is shipped with the installer. A patch of the changes we applied to the lib is in the setup as well.

Other things fixed:
- no longer using SDL_ListModes to filter available resolutions ( use +set r_useSDLModes to re-enable, SDL_ListModes returns way too little of the possible resolutions )
- fix stalls that may happen with DNS resolution ( Linux bug only )
- fix a download bug: if the server is configured with some of the fs_*path cvars having a trailing slash, they might cut one character when returning download URLs.

The download bug affects all operating systems. If you run a Windows server, make sure you don\'t have a trailing slash at the end of fs_basepath