BaseTools: Add NULL pointer check in AutoGen code
BaseTools: Add NULL pointer check in AutoGen code

For DynamicEx PCD, if NULL pointer is specified as token space GUID,
it will directly be used to compare GUID value in AutoGen code.
To avoid access NULL pointer, NULL pointer will be checked first.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>

git-svn-id: 3158a46dfd52e07d1fda3e32e1ab2e353a00b20f@18267 6f19259b-4bc3-4df7-8a09-765794883524

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2