BaseTools: Add build error detection for Dynamic PCD name conflict

BaseTools: Add build error detection for Dynamic PCD name conflict

when multiple Dynamic PCD have different token space guid but same PCD
name, it is difficult for user to check why the generated autogen.c and
autogen.h are not consistent. so we add a check before generating
autogen.c and report error directly that user can know what happened
immediately.

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@19027 6f19259b-4bc3-4df7-8a09-765794883524