Open-source X.org graphics driver for ARM graphics

DRM driver selection
While most operations use only the standard DRM modesetting interfaces, certain operations
unavoidably rely on specific driver behaviour (including dumb buffer allocation flags and cursor
plane z-ordering). As such, the armsoc driver must be configured for a particular DRM driver.

The currently supported DRM drivers are:
- pl111
- exynos

To configure armsoc for one of these, pass the --with-drmmode option to ./configure. For example:

$ ./configure --with-drmmode=pl111

For other drivers, you will need to implement this support yourself. A template implementation is
provided in src/drmmode_template which can be built by passing --with-drmmode=template to ./configure.
The interface is defined and documented in src/drmmode_driver.h, and you should refer to this while
modifying the template to set up your DRM driver's abstraction appropriately.

You can also copy src/drmmode_template into src/drmmode_<yourdrivername> and build with:

$ ./configure --with-drmmode=<yourdrivername>