Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Uuencode the sample "binary" firmware image file (instead of explicitly
adding \0 bytes). This is a technique that would be used in an actual
driver and is more suitable as an example.

Reviewed by: mlaier

Avoid having a binary file in our source tree and instead create it at
build time, to avoid possible grief maintaining FreeBSD source in
alternative version control tools.

firmware(9) is a subsystem to load binary data into the kernel via a
specially crafted module. There are several handrolled sollutions to this
problem in the tree already which will be replaced with this. They include
iwi(4), ipw(4), ispfw(4) and digi(4).

No objection from: arch
MFC after: 2 weeks
X-MFC after: some drivers have been converted