main: Move cancellable creation later

We should only be calling into GIO once we've set our preparatory
environment variables etc.  Not fixing anything today that I know
of, just noticed while looking at the code.

Closes: #1763
Approved by: jlebon

src/app/main.c

@@ -391,7 +391,6 @@ int
 main (int    argc,
       char **argv)
 {
-  GCancellable *cancellable = g_cancellable_new ();
   RpmOstreeCommand *command;
   const char *command_name = NULL;
   g_autofree char *prgname = NULL;
@@ -417,6 +416,8 @@ main (int    argc,
 
   setlocale (LC_ALL, "");
 
+  GCancellable *cancellable = g_cancellable_new ();
+
   /*
    * Parse the global options. We rearrange the options as
    * necessary, in order to pass relevant options through