Fixed Msys detection from gnumake

OSTYPE env var can't be used, as it's a bash only
env var, so instead use uname -o
ncurses WIP

Switching from PDCurses to ncurses to
investigate some mingwbuilds problems
Add final $prefix/bin to PATH

.. during make so that tcl/tk dlls are found
when the test import of _tkinter.pyd happens
Forward port msys-convert_path

.. changes from 2.7.5 to 3.3.0