correlate symbols also by type

Both unpatched and patched objects may contain FILE
symbol with empty name. This is unexpected for
create-diff-object and could correlate 2 symbols
with same (empty) name but different types:
  sym 00, type 0, bind 0, ndx 00, name  (SAME)
  ...
  sym 425, type 4, bind 0, ndx 65521, name  (SAME)
  ...
  signal.o: changed function: do_rt_tgsigqueueinfo
  signal.o: changed function: do_rt_sigqueueinfo
  signal.o: changed function: get_signal_to_deliver
  signal.o: signal.o: changed section .rela__jump_table not selected for inclusion
  signal.o: 1 unsupported section change(s)
  /root/kpatch/kpatch-build/create-diff-object: unreconcilable difference

Introduce condition to match symbols also by type.
Fixes #202 

Signed-off-by: Jan Stancek <jstancek@redhat.com>