lib: don't use uninitialized value "m"

*** CID 150397:  Memory - illegal accesses  (UNINIT)
/lib/criu.c: 696 in criu_local_add_irmap_path()
690
691             return 0;
692
693     err:
694             if (my_path)
695                     free(my_path);
>>> >>>     CID 150397:  Memory - illegal accesses  (UNINIT)
>>> >>>     Using uninitialized value "m".
696             if (m)
697                     free(m);
698
699             return -ENOMEM;
700     }
701

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>