pdu_parse_target: Add coap_show_pdu to test case

oss-fuzz: Added split_uri target
oss-fuzz: Update usage of coap_show_pdu() in pdu_parse_target
oss-fuzz: Fix split uri issue mentioned in #218
oss-fuzz: Set log level

tests/oss-fuzz/pdu_parse_target.c

@@ -4,7 +4,9 @@ int
 LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
     coap_pdu_t *pdu = coap_pdu_init(0, 0, 0, size);
     if (pdu) {
+        coap_set_log_level(LOG_DEBUG);
         coap_pdu_parse(COAP_PROTO_UDP, data, size, pdu);
+        coap_show_pdu(LOG_DEBUG, pdu);
         coap_delete_pdu(pdu);
     }
     return 0;

tests/oss-fuzz/split_uri_target.c

@@ -0,0 +1,8 @@
+#include <coap2/coap.h>
+
+int
+LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+    coap_uri_t uri;
+    coap_split_uri(data, size, &uri);
+    return 0;
+}