Fix a const warning under msvc

diff --git a/src/common/util.c b/src/common/util.c
index 61d09aa4a8dc6e58a990a3d6ae6047e3e2e23bd6..b0055d6c78b4b73e08d9740e30619ab250797c0d 100644 (file)
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -4919,7 +4919,7 @@ tor_check_port_forwarding(const char *filename,
     status = tor_spawn_background(filename, argv, NULL, &child_handle);
 #endif
 
-    tor_free(argv);
+    tor_free((void*)argv);
 
     if (PROCESS_STATUS_ERROR == status) {
       log_warn(LD_GENERAL, "Failed to start port forwarding helper %s",