Fix strict build

Signed-off-by: falkTX <falktx@falktx.com>

source/backend/plugin/CarlaPluginJack.cpp

@@ -1671,7 +1671,7 @@ public:
 
         // remove unprintable characters if needed
         if (fSetupHints & LIBJACK_FLAG_EXTERNAL_START)
-            fInfo.setupLabel[5] = '0' + (fSetupHints ^ LIBJACK_FLAG_EXTERNAL_START);
+            fInfo.setupLabel[5] = static_cast<char>('0' + (fSetupHints ^ LIBJACK_FLAG_EXTERNAL_START));
 
         return true;
     }

source/libjack/libjack_port-searching.cpp

@@ -331,7 +331,7 @@ const char** jack_port_get_all_connections(const jack_client_t* client, const ja
 {
     carla_stdout("%s(%p, %p) WIP", __FUNCTION__, client, port);
 
-    JackClientState* const jclient = (JackClientState*)client;
+    const JackClientState* const jclient = (const JackClientState*)client;
     CARLA_SAFE_ASSERT_RETURN(jclient != nullptr, nullptr);
 
     const JackPortState* const jport = (const JackPortState*)port;