install-exec and bdist_wheel also depend on version.py. Let's ensure
that version.py is correctly generated when installing or building
packages.

Yes, make is clever and correctly merges dependencies with rules from
included make files.

Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Milan Kubik <mkubik@redhat.com>

AC_CONFIG_FILES in configure.ac works well only with Makefiles.
Other files have to be handled by Makefile.am so depedencies
are tracked properly.

https://fedorahosted.org/freeipa/ticket/6498

Reviewed-By: Martin Basti <mbasti@redhat.com>

This version builds only one version of Python packages. If you want to
build for Python 2 & 3 call configure twice using different --with-python
or specify PYTHON variable when calling make.

dist-hook is using SOURCES.txt file from egg-info.
According to Petr Viktorin this should be enough for our purposes
and avoids need to create plugins for setuptools.

Currently VPATH builds do not work for various reasons.
This should be fixed later on.

Most credit goes to these guys:
 Christian Heimes <cheimes@redhat.com>
 Petr Viktorin <pviktori@redhat.com>
 Kevin Brown <kevin@kevin-brown.com>

https://fedorahosted.org/freeipa/ticket/6418

Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>