agl-compositor: Update SRCREV to use libweston7

agl-compositor: Update SRCREV to use libweston7

This includes the following changes (all of them related
to the libweston7 upgrade):

- dbba1adda7f meson.build: Increase version of the compositor
- b352cee6f81 meson.build: Build X11 backend optionally
- 93523a7f38b meson.build: Increase wayland-protocol version dependency
- c769a272324 main: Add support for the logging context when creating
the compositor instance
- a17bac48464 meson.build: Upgrade build and headers to libweston7

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: I94e5077c48eca76092306892d6e25e345eeda45e