videoout: Use the output overlay buffer type

The omap_vout driver implements the output overlay API, use the
corresponding buffer type.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
videoout: Return a negative error code in vo_queue_buffer()

Most functions return 0 on success and a negative error code otherwise,
make vo_queue_buffer() conform with that.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Ignore unused-paremeter warnings and link with libdl.
Ignore select timeouts (they happen when we pause the video stream).
Prefer scaling the image on the sensor (with binning).
Add keyboard handling. Load process_image from a shared object.
Add the source of a sample DSP processing library.
Add a new readme explaining this fork's functionality.
Revert "Prefer scaling the image on the sensor (with binning)."

This reverts commit 23f35a7e0ec4a624bd9c983665c79a344a2f062e.
Give back control to the DSP thread using a new dspthread.h API.
Add build and run.sh helper scripts.
Add the framebuffer disable command to README.
Disable fsp_show by default and make it switchable with the 'f' key.
Improve the dlopen failure error message.
Made the dspthread.h file C++ compatible.
Added 'scale-on-sensor' command-line option.

Does not work with AEWB yet.
Do not queue frames (busy=1) until dsp_getframe is called.
Enabled debugging symbols.
Moved library loading after ISP pipeline initialisation.
Makefile: Set default compiler and header paths.