Bugfix: Fix build with libblkmaker < 0.2
RPC: Avoid exposing Coinbase-Sig when it isn't supported
Bugfix: ztex: Avoid trying to format non-libusb error with libusb error name
Merge commit 'a705ab3' into bfgminer-2.10.x
Merge commit '81b88e3' into bfgminer-2.10.x

Conflicts:
	miner.c
Merge commit '9df747c' into bfgminer-2.10.x