b2g-info: Fix copyright year.
b2g-info: Make print_b2g_pids return void.
b2g-info: Switch to using TEMP_FAILURE_RETRY, and handle short reads.
b2g-info: Print a better error message if opening /proc/meminfo fails.
b2g-info: Display usage() if we receive an invalid arg.
b2g-info: Don't name variables |nice| and |stat|; those already exist as functions.