Add a new quilt patch with a fix to harden the `hbf2gf' and `*conv' binaries,...

Add a new quilt patch with a fix to harden the `hbf2gf' and `*conv' binaries, in particular to have "read-only reolcations" while compiling with GCC.  See https://wiki.debian.org/Hardening for more information on dpkg-buildflags.