ArmVirtPkg: apply PE/COFF memory protection to DxeCore as well

Include DXE_CORE in the BuildOptions that are set to force 4 KB section
alignment for PE/COFF images in order to allow them to be mapped with
strict memory permissions.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>