Port setup.py to setuptools.

Upstream-Status: Submitted [https://github.com/ldo/dbussy/pull/53]
Signed-off-by: Ross Burton <ross.burton@arm.com>

diff --git a/setup.py b/setup.py
index 4b9411e..da7ee7e 100644
--- a/setup.py
+++ b/setup.py
@@ -8,33 +8,9 @@
 # Written by Lawrence D'Oliveiro <ldo@geek-central.gen.nz>.
 #-
 
-import sys
-import distutils.core
-from distutils.command.build import \
-    build as std_build
+import setuptools
 
-class my_build(std_build) :
-    "customization of build to perform additional validation."
-
-    def run(self) :
-        try :
-            exec \
-              (
-                "async def dummy() :\n"
-                "    pass\n"
-                "#end dummy\n"
-              )
-        except SyntaxError :
-            sys.stderr.write("This module requires Python 3.5 or later.\n")
-            sys.exit(-1)
-        #end try
-        super().run()
-    #end run
-
-#end my_build
-
-distutils.core.setup \
-  (
+setuptools.setup(
     name = "DBussy",
     version = "1.3",
     description = "language bindings for libdbus, for Python 3.5 or later",
@@ -43,9 +19,5 @@ distutils.core.setup \
     author_email = "ldo@geek-central.gen.nz",
     url = "https://github.com/ldo/dbussy",
     license = "LGPL v2.1+",
     py_modules = ["dbussy", "ravel"],
-    cmdclass =
-        {
-            "build" : my_build,
-        },
-  )
+)