[python3] adjust sysconfig include dir to match vcpkg layout

[Neumann-A]

Fixes #34876

[m-kuhn]

@Neumann-A

This looks unexpected to me (and breaks my attempts to build PyQt6 where Python.h is not found due to a wrong include path):

./tools/python3/python3.11 -c "import pprint;import sysconfig; pprint.pprint(sysconfig.get_paths())"                                                                     
{'data': '/home/mkuhn/dev/vcpkg/installed/x64-linux',
 'include': '/home/mkuhn/dev/vcpkg/include/python3.11',
 'platinclude': '/home/mkuhn/dev/vcpkg/include/python3.11',
 'platlib': '/home/mkuhn/dev/vcpkg/installed/x64-linux/lib/python3.11/site-packages',
 'platstdlib': '/home/mkuhn/dev/vcpkg/installed/x64-linux/lib/python3.11',
 'purelib': '/home/mkuhn/dev/vcpkg/installed/x64-linux/lib/python3.11/site-packages',
 'scripts': '/home/mkuhn/dev/vcpkg/installed/x64-linux/bin',
 'stdlib': '/home/mkuhn/dev/vcpkg/installed/x64-linux/lib/python3.11'}

[m-kuhn]

Looks fine on windows:

import pprint;import sysconfig; pprint.pprint(sysconfig.get_paths())
{'data': 'C:\\Users\\Public\\dev\\vcpkg\\installed\\x64-windows\\tools\\python3',
 'include': 'C:\\Users\\Public\\dev\\vcpkg\\installed\\x64-windows\\include\\python3.11',
 'platinclude': 'C:\\Users\\Public\\dev\\vcpkg\\installed\\x64-windows\\include\\python3.11',
 'platlib': 'C:\\Users\\Public\\dev\\vcpkg\\installed\\x64-windows\\tools\\python3\\Lib\\site-packages',
 'platstdlib': 'C:\\Users\\Public\\dev\\vcpkg\\installed\\x64-windows\\tools\\python3\\Lib',
 'purelib': 'C:\\Users\\Public\\dev\\vcpkg\\installed\\x64-windows\\tools\\python3\\Lib\\site-packages',
 'scripts': 'C:\\Users\\Public\\dev\\vcpkg\\installed\\x64-windows\\tools\\python3\\Scripts',
 'stdlib': 'C:\\Users\\Public\\dev\\vcpkg\\installed\\x64-windows\\tools\\python3\\Lib'}