softpipe: Initial work on Gallium renderer

* This is still early, but I want to track the
development in tree.
* swpipe will support Gallium softpipe or llvmpipe
(llvm pipe will give improved software rendering
permance when llvm is included at os build time)
* Used Artur Wyszynski's original code as a
road map... however a *lot* has changed.
* Crashes at startup.. not in image yet