gcc -O3 complains about uninitialized use of 'nims'. In fact,
inm_get_source() can return an error without setting nims which will
be later read from RB_FOREACH_REVERSE_FROM macro. It looks like 'nims'
is intended to hold the last value for which inm_get_source() returned
success. The uninitialized access would happen if this function never
succeded. I am not sure if this is possible in practice, but let's
initialize nims to NULL, which will cause no iteration in
RB_FOREACH_REVERSE_FROM macro.

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>