build breakage on DVB-only configuration

[Robert Tsai <rtsai1111>]

Latest SVN build breakage:

g++  -o mythepg main.o    -L/usr/share/qt3/lib -L../../libs/libmyth -L../../libs/libmythtv -L../../libs/libavcodec -L../../libs/libavformat -lmythtv-0.18 -lmythavformat-0.18 -lmythavcodec-0.18 -lmyth-0.18 -lfreetype -lmp3lame -lasound -ldvdnav -L/usr/X11R6/lib -lXinerama -lXv -lXxf86vm -lGL -lGLU -lqt-mt -lXext -lX11 -lm -lpthread
../../libs/libmythtv/libmythtv-0.18.so: undefined reference to `Channel::Open()'
../../libs/libmythtv/libmythtv-0.18.so: undefined reference to `Channel::Close()'
../../libs/libmythtv/libmythtv-0.18.so: undefined reference to `Channel::IsTuned() const'
../../libs/libmythtv/libmythtv-0.18.so: undefined reference to `Channel::Tune(unsigned, QString, QString)'
../../libs/libmythtv/libmythtv-0.18.so: undefined reference to `Channel::Channel[in-charge](TVRec*, QString const&)'
../../libs/libmythtv/libmythtv-0.18.so: undefined reference to `Channel::~Channel [in-charge]()'
collect2: ld returned 1 exit status
make[2]: *** [mythepg] Error 1
make[2]: Leaving directory `/home/rtsai/src/packages/mythtv/mythtv/programs/mythepg'

I'm not sure whether channel.h and channel.cpp should be moved out of the using_v4l section of libmythtv.pro, or if the EPG code should somehow not be depending on channel.cpp code.

[Robert Tsai <rtsai1111>]

(Moving the channel.h and channel.cpp bits up into the using_backend section allows things to build for me.)

[Isaac Richards]

(In [6808]) Move analogscan to the using_v4l case only. Fixes #93.