Singular/Sources — pull request #226 by alexanderdreyer (2012-12-10 23:52:34+00:00)
Title: Fix nonexisting or old python won't break build

As malex had pointed out, this would break build on system's, which has outdated python. I realized, that would also break on systems without any python. I've added the macro `AX_PYTHON_WITH_VERSION` which deals with that issue to a separate m4 file. (Is this the right convention?)