[Distutils] Patch for install.py from Distutils-1.0

On Windows one will often get the warning message "warning: install: modules installed to 'c:\Python20\', which is not in Python's module search path (sys.path) -- you'll have to change the search path yourself", even though the named directory is in fact in the user's PYTHONPATH. The problem is that the install command is using a case-sensitive comparision of the path names and Python reports this path entry as "c:\python20" (note the lowercase "p"). So the comparison fails and the install command emits this false warning. The attached patch to the current cvs version of install.py should correct the problem.