[mythtv] compile error with subversion r7408 / gcc4

[Adam Forsyth]

firewirerecorder.cpp: In member function 'virtual bool
FirewireRecorder::PauseAndWait(int)':
firewirerecorder.cpp:252: error: invalid use of undefined type 'struct TVRec'
recorderbase.h:13: error: forward declaration of 'struct TVRec'
make[2]: *** [firewirerecorder.o] Error 1