Include real weston compositor header(s)

Include real weston compositor header(s)

Weston does not install any headers to aid weston module
development.

Thus, the weston headers should be copied/symlinked from the
weston source tree to this source tree so we can build our
weston-wfits module/extension:

compositor.h -> src/extensions/weston/weston-headers/core/.
matrix.h -> src/extensions/weston/weston-headers/shared/.
config-parser.h -> src/extensions/weston-headers/shared/.

This is done automatically by the wayland-scripts build
hooks.  Otherwise, you will have to do it manually.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>