debian: Make liblopsub-dev usable for cross compilation.

debian: Make liblopsub-dev usable for cross compilation.

In order to build a package such as tfortune which depends on the
lopsub library, we need the liblopsub shared library for the host
architecture, and we also need to run lopsubgen as a build architecture
executable. These things currently reside in the same binary package,
but for a cross build we need them to be installed for different
architectures.

This patch splits liblopsub-dev. The new liblopsub-bin package only
contains lopsubgen and its man page. Since the -dev package depends
on the -bin package, all existing uses will continue to work as
is. For a cross build, liblopsub-dev will continue to be installed
for the host architecture. liblopsub-bin will be installed for the
build architecture though as it will be marked Multi-Arch: foreign,
indicating that the architecture of the package does not matter for
interactions with it.

V3: Edit debian/changelog since this is no longer an NMU, add signed-off-by
V2: Add missing "Multi-Arch: same" for liblopsub1t64, fix typo

Signed-off-by: Andre Noll <maan@tuebingen.mpg.de>