Backport some warning fixes from default branch
Fix another perl warning
Add configure check for e-d-s being lower than 3.6. Refs #15353
Fix the last ppc64 warning
Add missing typedef
Fix build of Finch against Python3.

Fixes #15969.
Use python-config to find Python headers and libraries.

The current method does not work with Python 3 in Fedora, as the
binary, headers, and libraries are suffixed with '3.3m'. The current
test checks the internal version of Python and see '3.3.2' -> '3.3'.
Fix call to Py_SetProgramName in Python3.

Refs #15969.
Fix make distcheck for 2.x.y
Backport 843aba5973db to 2.x.y
Fix make distcheck for 2.x.y: clean outstanding perl files
Fix another perl cleanup failure