pythongh-202: Simply Windows installation

doc/usage.rst

@@ -23,27 +23,6 @@ extension. Commands on Fedora to install dependencies:
 * Python 3: ``sudo dnf install python3-devel``
 * PyPy: ``sudo dnf install pypy-devel``
 
-Windows notes
--------------
-
-On Windows, to allow pyperformance to build dependencies from source
-like ``greenlet``, ``dulwich`` or ``psutil``, if you want to use a
-``python.exe`` built from source, you should not use the ``python.exe``
-directly. Instead, you must run the little-known command ``PC\layout``
-to create a filesystem layout that resembles an installed Python::
-
-    .\python.bat -m PC.layout --preset-default --copy installed -v
-
-(Use the ``--help`` flag for more info about ``PC\layout``.)
-
-Now you can use the "installed" Python executable::
-
-    installed\python.exe -m pip install pyperformance
-    installed\python.exe -m pyperformance run ...
-
-Using an *actually* installed Python executable (e.g. via ``py``)
-works fine too.
-
 
 Run benchmarks
 ==============

pyperformance/venv.py

@@ -137,6 +137,12 @@ def _get_envvars(inherit=None, osname=None):
         copy_env.extend(inherit)
 
     env = {}
+    # Recent setuptools versions have a bug that prevents being
+    # used to compile from a source build virtual environment.
+    # [BUG](https://github.com/pypa/setuptools/issues/3325)
+    # The stdlib distutils does not have this problem.
+    if os.name == 'nt':
+        env['SETUPTOOLS_USE_DISTUTILS'] = 'stdlib'
     for name in copy_env:
         if name in os.environ:
             env[name] = os.environ[name]