The sole caller of exit_inferior_num_silent was getting the inferior's
number to then use the number to look up the inferior again. I think
it's better to simply not have exit_inferior_num_silent; any potential
callers that only have the inferior's number should probably be
converted to pass the inferior itself around instead.
Tested by the buildbot.
gdb/ChangeLog
2018-07-03 Tom Tromey <tom@tromey.com>