Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Synchronize with latest upstream VCHI code:

- Add LIB_VERSION ioctl
- Add CLOSE_DELIVERED ioctl
- Bump code version

Upstream version: 3782f2ad42c08f4d32f64138f8be7341afc380f5

Do not mark shared structures as __packed, it leads to race condition

If structure packed as __packed clang (and probably gcc) generates
code that loads word fields (e.g. tx_pos) byte-by-byte and if it's
modified by VideoCore in the same time as ARM loads the value result
is going to be mixed combination of bytes from previous value and
new one.

Import VCHI driver for Broadcom's VideoCore IV GPU

Differential Revision: D1753