Add a preprocessor protocol name variable

We should convert - to _ in the preprocessor protocol name since - will
lead to a new token, but we don't since it is better to fail early here
and the official wayland-scanner doesn't do this either. The generated
c++ header will give a compiler error when being used which gives the
user a chance to change the protocol name.

Change-Id: I049bdecacc8ed9a70c0879494d4d358ce53f3320
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
Add hardware integration protocol

This sends to clients what HW integration is being used in the
compositor. This is useful when the wayland clients are loading their
buffer integrations with plugins since they then can pick the correct
plugin automatically.

Change-Id: Ib4eac3b855c6772ac1581b7f06aa929aeb1a1db0
Reviewed-by: Andy Nichols <andy.nichols@digia.com>