Replace EFI_IMAGE_NT_HEADERS usage with EFI_IMAGE_OPTIONAL_HEADER_UNION.
Replace EFI_IMAGE_NT_HEADERS usage with EFI_IMAGE_OPTIONAL_HEADER_UNION.

EFI_IMAGE_NT_HEADERS depends on the value of the ARCH environment variable
at the time the BaseTools are built.  This tool should handle all images
architecture and have no dependencies on the architecture of the build
machine.

This change fixes a build error where on x86-64 Linux, the build ARCH
will be X64, and therefore EFI_IMAGE_NT_HEADERS will not have a
BaseOfData member.

This change does not ensure that all input & output images will be
properly handled.  In fact, this tool should be referencing
EFI_IMAGE_OPTIONAL_HEADER_UNION.Pe32Plus to properly support 64-bit
images.

git-svn-id: f3880c1fc5096ce2109c8aec392d8e07f619f417@1647 c2973edb-eda0-4c78-bc6a-9341b269661f

bitcrystal/buildtools-BaseTools,bitcrystal/buildtools-BaseTools,tianocore/buildtools-BaseTools,tianocore/buildtools-BaseTools,bitcrystal/buildtools-BaseTools,bitcrystal/buildtools-BaseTools,tianocore/buildtools-BaseTools,tianocore/buildtools-BaseTools,tianocore/buildtools-BaseTools,bitcrystal/buildtools-BaseTools