fix setup.py on windows

appveyor.yml

@@ -109,7 +109,7 @@ build_script:
     b2.exe --hash openssl-lib=%ssl_lib% openssl-include=%ssl_include% warnings=all -j %NUMBER_OF_PROCESSORS% %compiler% address-model=%model% picker-debugging=on invariant-checks=full variant=%variant% link=shared crypto=%crypto% asserts=on export-extra=on windows-api=%api% windows-version=win10 libtorrent-link=shared stage_module stage_dependencies
     )
   - if defined python_dist (
-    c:\Python35-x64\python.exe setup.py bdist --format=msi
+    c:\Python36-x64\python.exe setup.py bdist --format=msi
     )
 
   # simulations

bindings/python/setup.py

@@ -7,14 +7,15 @@
 import sys
 import sysconfig
 import tempfile
+import multiprocessing
 
 import setuptools
 import setuptools.command.build_ext as _build_ext_lib
 
 
 def get_msvc_toolset():
     # Reference: https://wiki.python.org/moin/WindowsCompilers
-    major_minor = sys.version_info()[0:2]
+    major_minor = sys.version_info[0:2]
     if major_minor in ((2, 6), (2, 7), (3, 0), (3, 1), (3, 2)):
         return "msvc-9.0"
     if major_minor in ((3, 3), (3, 4)):
@@ -96,7 +97,8 @@ def write_b2_python_config(config):
     # python.jam appends SHLIB_SUFFIX on its own.
     ext_suffix = sysconfig.get_config_var("EXT_SUFFIX")
     shlib_suffix = sysconfig.get_config_var("SHLIB_SUFFIX")
-    ext_suffix = ext_suffix[: -len(shlib_suffix)]
+    if shlib_suffix != None and len(shlib_suffix) < len(ext_suffix):
+        ext_suffix = ext_suffix[: -len(shlib_suffix)]
     write(f' : "{ext_suffix}"')
     write(" ;\n")
 
@@ -193,7 +195,9 @@ def build_extension_with_b2(self):
             self.announce("project-config.jam contents:")
             self.announce(config.read())
             config.close()
+            args.append(f"python={sysconfig.get_python_version()}")
             args.append(f"--project-config={config.name}")
+            args.append(f"-j{multiprocessing.cpu_count()}")
             self.spawn(["b2"] + args)
         finally:
             os.unlink(config.name)