stbt.ocr: Include frame_repr in debug output
stbt.ocr: Include frame_repr in debug output

So that we can see the exact timestamp of the frame that was
processed (not the timestamp when the debug message was printed).

stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester