test_nta_api.c: removed warnings about signedness
test_nta_api.c: removed warnings about signedness

darcs-hash:20071005085845-88462-fd84173852664720e56488097427918d148a1f80.gz

jart/sofia-sip,xhook/sofia-sip,xhook/sofia-sip,unispeech/sofia-sip,jart/sofia-sip,xhook/sofia-sip,unispeech/sofia-sip,BelledonneCommunications/sofia-sip,BelledonneCommunications/sofia-sip,erdincay/sofia-sip,unispeech/sofia-sip,BelledonneCommunications/sofia-sip,xhook/sofia-sip,erdincay/sofia-sip,BelledonneCommunications/sofia-sip,erdincay/sofia-sip,xhook/sofia-sip,erdincay/sofia-sip,jart/sofia-sip,unispeech/sofia-sip