fuzz: use some value for max_pending_packets

so as not to timeout waiting forever for the condition
in PacketPoolWait

src/tests/fuzz/fuzz_decodepcapfile.c

@@ -74,6 +74,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
         tmm_modules[TMM_DECODEPCAPFILE].ThreadInit(tv, NULL, (void **) &dtv);
         (void)SC_ATOMIC_SET(tv->tm_slots->slot_next->slot_data, dtv);
 
+        extern intmax_t max_pending_packets;
+        max_pending_packets = 128;
         PacketPoolInit();
 
         initialized = 1;

src/tests/fuzz/fuzz_sigpcap.c

@@ -81,6 +81,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
         tmm_modules[TMM_FLOWWORKER].ThreadInit(&tv, NULL, &fwd);
         StatsSetupPrivate(&tv);
 
+        extern intmax_t max_pending_packets;
+        max_pending_packets = 128;
         PacketPoolInit();
         initialized = 1;
     }