python_2.7.5.oe: Remove copy-paste from zlib
python.inc: Review finding - use lib* format
python.inc: use variables instead of hard-coded paths
Python-2.7.5-xcompile.patch: Remove the need for special naming

Remove the part from the patch which results in a requirement
that the python used to create the Machine python is named:
python_for_build.
Furthermore the naming of pgen is changed from pgen_native to
simply just pgen
python.inc: Avoid special naming of python/pgen

Avoid naming the native build python for python_native/python_for_build.
The changes goes along with a patch update