BaseTools: Fix GenSec GCC make failure

BaseTools: Fix GenSec GCC make failure

It is a regression bug introduced by the patch b37b108, it cause GenSec
make failure on GCC Env.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>