[Discuss-gnuradio] tiny kalibrator fix

[suraev]

Hello.

I'm not sure to which list this should go: there is no "kal" tool in  
the openbts git atm but gnuradio wiki where kal-0.2 is available says  
that it will be there eventually.

Nevertheless kal build failed on ubuntu 10.04.2 x86 with gcc 4.4.3 due  
to lack of "#include <stdio.h>" in circular_buffer.cc

It would be nice to see this trivial fix merged in some proper location.

cheers,
Max.