fuzz: init reverse before calling AppLayerProtoDetectGetProto

Completes commit fec06f8ac3

The 2 callers in suricata itself already do that

src/tests/fuzz/fuzz_applayerprotodetectgetproto.c

@@ -26,7 +26,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 {
     Flow *f;
     TcpSession ssn;
-    bool reverse;
+    bool reverse = false;
 
     if (alpd_tctx == NULL) {
         //global init