lircd: Allow drivers to terminate lircd using SIGUSR1.
lircd: Allow drivers to terminate lircd using SIGUSR1.

Used when doing regression tests. Clean up signal handling.

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