detect/files: fix buffer tracking with multiple files

src/detect-filemagic.c

@@ -554,6 +554,7 @@ static void PrefilterTxFilemagic(DetectEngineThreadCtx *det_ctx,
                         &det_ctx->mtcu, &det_ctx->pmq,
                         buffer->inspect, buffer->inspect_len);
             }
+            local_file_id++;
         }
     }
 }

src/detect-filename.c

@@ -460,6 +460,7 @@ static void PrefilterTxFilename(DetectEngineThreadCtx *det_ctx,
                         &det_ctx->mtcu, &det_ctx->pmq,
                         buffer->inspect, buffer->inspect_len);
             }
+            local_file_id++;
         }
     }
 }