libvlc: call exit() if command line help was requested

A library should not call exit(), but I do not see any easy way around
it: if libvlc_new() returns NULL on error so real errors cannot be
distinguished from --help stuff. Also --daemon already calls exit()
(through daemon()).

This introduces an O(1) memory leak when calling --help. It could be
fixed by merging libvlc_InternalCreate() and libvlc_InternalInit().

src/libvlc.c

@@ -224,7 +224,7 @@ int libvlc_InternalInit( libvlc_int_t *p_libvlc, int i_argc,
     if (config_PrintHelp (VLC_OBJECT(p_libvlc)))
     {
         module_EndBank (true);
-        return VLC_EEXITSUCCESS;
+        exit(0);
     }
 
     if( module_count <= 1 )