* Add a --with-module-dir configure parameter.

* Pass the moduledir into the wrapper.  Use it to construct the path to search
  for drivers.  Require drivers to end in a ".1" version, in case we ever want
  to rev. the interface between the wrapper and the drivers.

* If no driver is found in the new module dir, look for one in the default
  search paths.  This is intended to find libvdpau_nvidia.so for drivers that
  predate the change to move it, and can be removed in the future.

* Stash the moduledir into vdpau.pc.  Drivers can find this with
  `pkg-config --variable=moduledir vdpau`.

* Add a version to libvdpau_trace.so in case the interface between it and
  libvdpau.so ever changes.

* Install libvdpau_trace.so.1 to moduledir instead of libdir.

Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Acked-by: Stephen Warren <swarren@nvidia.com>