Update to upstream version '2.3.4'
with Debian dir 1e2db596e3ca6d19199090c7c18b13ffc2ea39de

..or else make(1) attempts to run dh for targets which
has dependencies but no rules ("phony" targets)

This one is the best of all so far, running dpkg-architecture
once to define all variables in one go.

This should really be put into architecture.mk

This change and previous clean target change makes running
thigs significantly more comfortable.

move build system leftovers into debian/clean, and list
only things which *should* be cleaned up in d/rules.
This way we only need to use single dh_clean invocation
which does everything (it does dh_testdir too), so we
do not need override_dh_auto_clean.

Not only remove the _PUBLIC_ markers from symbol declarations,
but also remove definition of _PUBLIC_ itself, or else it might
interfere even with samba own internal headers.  We should not
pollute a reserver namespace anyway.

this stop re-running configure on each build

It is not specific to a python version.
This also allows us to remove override_dh_install rule
and remove custom variable usage from .install file

The _PUBLIC_ marking for every symbol in a public header file is
wrong, _PUBLIC_ can be #defined by some other module when including
this file, and the compilation or link will fail. The markings
should be done in the source files instead. More, _PUBLIC_ falls into
reserved namespace which should not be (ab)used.