buildtools: Honor LDVERSION when looking for Python library

buildtools: Honor LDVERSION when looking for Python library

Since Python 3.2, Python .so files are tagged for ABI compatibility,
so the library name is something like libpython3.4m.so (note the 'm').
This information is found in distutils.sysconfig.get_config_var('LDVERSION')

This fixes waf issue 1405 (https://code.google.com/p/waf/issues/detail?id=1405)

Signed-off-by: Petr Viktorin <pviktori@redhat.com>
Reviewed-By: Jelmer Vernooij <jelmer@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>