app-layer: add logger check to API

The new API call:
    int AppLayerParserProtocolHasLogger(uint8_t ipproto,
                                        AppProto alproto)

Returns TRUE if a logger is registered on the ip/alproto pair, and
FALSE otherwise.

src/app-layer-parser.c

@@ -943,6 +943,14 @@ int AppLayerParserProtocolSupportsTxs(uint8_t ipproto, AppProto alproto)
     SCReturnInt(r);
 }
 
+int AppLayerParserProtocolHasLogger(uint8_t ipproto, AppProto alproto)
+{
+    SCEnter();
+    int ipproto_map = FlowGetProtoMapping(ipproto);
+    int r = (alp_ctx.ctxs[ipproto_map][alproto].logger == 0) ? 0 : 1;
+    SCReturnInt(r);
+}
+
 void AppLayerParserTriggerRawStreamReassembly(Flow *f)
 {
     SCEnter();

src/app-layer-parser.h

@@ -185,6 +185,7 @@ int AppLayerParserHasDecoderEvents(uint8_t ipproto, AppProto alproto, void *alst
 int AppLayerParserProtocolIsTxAware(uint8_t ipproto, AppProto alproto);
 int AppLayerParserProtocolIsTxEventAware(uint8_t ipproto, AppProto alproto);
 int AppLayerParserProtocolSupportsTxs(uint8_t ipproto, AppProto alproto);
+int AppLayerParserProtocolHasLogger(uint8_t ipproto, AppProto alproto);
 void AppLayerParserTriggerRawStreamReassembly(Flow *f);
 
 /***** Cleanup *****/