[PATCH v2] build: make gpudev optional

[Thomas Monjalon]

17/11/2021 22:39, eagostini at nvidia.com:
> From: Elena Agostini <eagostini at nvidia.com>
> 
> This library can be made optional.
> drivers/gpu and app/test-gpudev depend on this library,
> so there is a check for dependencies.

Changed to
so they are automatically disabled if the lib is disabled.

> Signed-off-by: Elena Agostini <eagostini at nvidia.com>

Applied with blank lines fixed.