dvblast: new package

DVBlast is a simple and powerful MPEG-2/TS demux and streaming
application.

[Thomas:
 - add missing hash file.
 - rewrap Config.in help text
 - remove unneeded "DVBLAST_INSTALL_TARGET = YES", since this is the
   default behavior
 - pass TARGET_MAKE_ENV in the environment when calling make.
 - use TARGET_CONFIGURE_OPTS instead of just CC/LD.]

Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>