Catch the termcap exception if there's a problem looking the terminal up.

Catch the termcap exception if there's a problem looking the terminal up.
It's just a progressmeter after all, there's no reason to error out instead
of simply devolving to "no progress meter".

(as noticed working with one of my students, Matthieu Fourre, whose
emulator or setup was somehow passing an "xterm-kitty" string)