The tile cache is a utility, it shouldn't know anything about the
entity which is making use of it (ie softpipe).
Remove softpipe parameter to all the tilecache function calls, and
also remove the need to keep a softpipe pointer in the sampler structs.
Update the Makefiles and includes for the new paths.
Note that there hasn't been no separation of the Makefiles yet, and make is
jumping all over the place. That will be taken care shortly. But for now, make
should work. It was tested with linux and linux-dri. Linux-cell and linux-llvm
might require some minor tweaks.
