[Patches] Fix main Makefile to create prefix, exec_prefix

[Guido van Rossum]

> Greg Ward writes:
>  > This patch fixes the top Python Makefile so it creates $(prefix) or
>  > $(exec_prefix) before attempting to create directories under them.
>  > Handy when you use prefixes like "/usr/local/python-1.5.2" and
>  > "/usr/local/python-1.6a1", which don't exist until you install Python
> 
>   I say check it in.  If Guido disagrees he can yell/email about it
> later; this is quite reasonable given the recent discussion of "stow"
> and the need of developers to keep multiple versions (including patch
> levels!) installed.

I still don't like it.  Let's discuss this face-to-face.

My argument why it doesn't do this (where I know that it easily
could!) is that if root makes a typo and says

  make install prefix=/usr/kocal

it will happily create /usr/kocal.  I think this is bad.

--Guido van Rossum (home page: http://www.python.org/~guido/)