Make plugin loading work on MacOS and Linux

etc/plugins/TGrid/P010_TJAlien.C

@@ -87,7 +87,7 @@ void P010_TJAlien()
     SetJAliEnSettings();
    }
 
-   if (gSystem->Load("libJAliEnROOT.so")>=0) {
+   if (gSystem->Load("libJAliEnROOT")>=0) {
       gPluginMgr->AddHandler("TGrid", "^alien:?", "TJAlien",
                              "JAliEnROOT", "TJAlien(const char*, const char*, const char*, const char*)");
    } else {