Fix a bug about large file support.

Reviewed-by: Star Zeng <star.zeng@intel.com>
Signed-off-by: Yingke Liu <yingke.d.liu@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2-buildtools/code/trunk/BaseTools@2612 c2973edb-eda0-4c78-bc6a-9341b269661f