We install nxssh in /opt/nx/bin.

N.B. Compilation requires libxcomp-dev as a prerequisite, although the
configure script doesn't check for it.

nxssh-3.5.0-2.tar.gz was used to build nxssh for Jessie, nxssh-6.7.6.tar.gz
for Stretch and Buster.

I don't seem to have adequately documented how I built nxssh for Buster.  It
looks like the sources can't be built against OpenSSL 1.0, and so I built it
on Stretch using OpenSSL 1.0.2 instead, and then used patchelf to include
/usr/lib/vmware in RUNPATH so that it can make use of Horizon Client's private
copy of OpenSSL 1.0.2 at runtime.

It also appears that I tweaked some files, probably for compatibility with a
later version of OpenSSL 1.0.x than the sources were intended for.  I have put
these changes in nxssh-6.7.6-mystery-patch.patch.