This will be used in packages that depend on gnu-efi, and we take this
opportunity to propagate this dependency where it was missing in
gummiboot and syslinux. In practice, it was not a problem because
gummiboot and syslinux are only available on i386 and x86-64, which is
a subset of the architectures supported by gnu-efi.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>