BaseTools: Enhance GenFv Tool to report error message

BaseTools: Enhance GenFv Tool to report error message

When two vtf files in one FV image, no FV file can be generated, but it
report the stack trace info. so we enhance the tool to report error
message directly but not the stack trace info.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19141 6f19259b-4bc3-4df7-8a09-765794883524