Pull request for UEFI sub-system for efi-2020-01-rc3
The following changes for the UEFI subsystem are provided:
* allow building UEFI binaries on the sandbox
* enable access to file systems without partition tables
* correctly check the return value of efi_dp_from_file()
On the sandbox the UEFI binaries must match the host architectures.
Adjust the Makefiles. Provide the PE/COFF header and relocation files.
Allow building helloworld.efi on the sandbox.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>