libmultipath: cleanup pthread_cleanup_pop call

libmultipath: cleanup pthread_cleanup_pop call

pthread_cleanup_push() and pthread_cleanup_pop() must be called in the
same lexical scope.  In uevent_listen(), the pthread_cleanup_pop() call
to cleanup the udev monitor is called in a nested 'if' block, within
the block where pthread_cleanup_push() is called.  Since this is a
single-statement if block, it doesn't actually cause any problems, but
it should be fixed anyways.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>