BaseTools/UPT: Fix a install issue

Fix a corner case issue of installing a module without
any files which causes installing UNI file failure

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hess Chen <hesheng.chen@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>
1 file changed