The official build instructions mandate usage of out-of-tree builds in
the build subdirectory. Replace the list of generated files in
.gitignore with just the build directory.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[Remove all other .gitignore entries]
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Split the project into a UVC gadget library and a test application. To
avoid rolling out a custom build system, switch to CMake.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>