package: add objcopy and ranlib to HOST_CONFIGURE_OPTS

This commit adds the OBJCOPY and RANLIB variables to
HOST_CONFIGURE_OPTS, since grub legacy will need these defined in
order to build properly.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>