Some cleanup:

countries.h: fix mismatch in declaration of country_code_array
countries.c: include countries.h
udp-filter.h: remove explicit initializers and add MAX_FILTER
udp-filter.c: use enums and bool to improve readability; replace
  strsep with strchr; remove
  * commented out code
  * unnecessary variables num_predefined_filters, j, n, ua, response_size
  * unnecessary for/switch
  * unnecessary initialization of fields array
  * unnecessary feof() call

Change-Id: Ibd6d67a9084a5e50f9c3a287c8051002973269f3
Merge "Some cleanup:"