util: Silence signed-unsigned comparison warnings

Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
draw: revert using correct order for prim decomposition.

This reverts db3dfcfe90a3d27e6020e0d3642f8ab0330e57be.
The commit was correct but we've got some precision problems later in
llvmpipe (or possibly in draw clip) due to the vertices coming in in
different order, causing some internal test failures. So revert for now.
(Will only affect drivers which actually support constant-interpolated
attributes and not just flatshading.)
vc4: Drop a weird argument in the BOs-from-handles API.
vc4: Add dmabuf support.

This gets DRI3 working on modesetting with glamor.  It's not enabled under
simulation, because it looks like handing our dumb-allocated buffers off
to the server doesn't actually work for the server's rendering.
vc4: Add a userspace BO cache.

Since our kernel BOs require CMA allocation, and the use of them requires
new mmaps, it's pretty expensive and we should avoid it if possible.
Copying my original design for Intel, make a userspace cache that reuses
BOs that haven't been shared to other processes but frees BOs that have
sat in the cache for over a second.

Improves glxgears framerate on RPi by around 30%.