Silence GCC-4.2 warning / possible GCC-4.3 error

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@10781 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/endpoints/mod_opal/mod_opal.cpp

@@ -82,7 +82,7 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_opal_load) {
 
     /* Prevent the loading of OPAL codecs via "plug ins", this is a directory
        full of DLLs that will be loaded automatically. */
-    putenv("PTLIBPLUGINDIR=/no/thanks");
+    putenv((char *)"PTLIBPLUGINDIR=/no/thanks");
 
 
     *module_interface = switch_loadable_module_create_module_interface(pool, modname);