Revert "python/Makefile.am: rely on global AM_INIT_AUTOMAKE"
libxml2 2.10.0 change the minimal automake requirement from no limitation to > 1.15 by 9e304353. Since CentOS 7 only coming with automake 1.13.4, now the minor upgrade from 2.9.x to 2.10.0 become broken.
This PR downgrade the automake minimal requirement from 1.15 to 1.13.4, which keep CentOS 7 complie for rpm functioning.
This reverts commit 9e304353.