Add asyncio event loop implementation

This is usable only on python >= 3.4 (or 3.3 with out-of-tree asyncio),
however it should be harmless for anyone with older python versions.

In simplest case, to have the callbacks queued on the default loop:

    >>> import libvirtaio
    >>> libvirtaio.virEventRegisterAsyncIOImpl()

The function is not present on non-compatible platforms.

Signed-off-by: Wojtek Porczyk <woju@invisiblethingslab.com>

setup.py

@@ -14,6 +14,7 @@ import sys
 import os
 import os.path
 import re
+import shutil
 import time
 
 MIN_LIBVIRT = "0.9.11"
@@ -50,6 +51,12 @@ def have_libvirt_lxc():
     except DistutilsExecError:
         return False
 
+def have_libvirtaio():
+    # This depends on asyncio, which in turn depends on "yield from" syntax.
+    # The asyncio module itself is in standard library since 3.4, but there is
+    # an out-of-tree version compatible with 3.3.
+    return sys.version_info >= (3, 3)
+
 def get_pkgconfig_data(args, mod, required=True):
     """Run pkg-config to and return content associated with it"""
     f = os.popen("%s %s %s" % (get_pkgcfg(), " ".join(args), mod))
@@ -124,6 +131,9 @@ def get_module_lists():
         c_modules.append(modulelxc)
         py_modules.append("libvirt_lxc")
 
+    if have_libvirtaio():
+        py_modules.append("libvirtaio")
+
     return c_modules, py_modules
 
 
@@ -141,6 +151,8 @@ class my_build(build):
         self.spawn([sys.executable, "generator.py", "libvirt-qemu", apis[1]])
         if have_libvirt_lxc():
             self.spawn([sys.executable, "generator.py", "libvirt-lxc", apis[2]])
+        if have_libvirtaio():
+            shutil.copy('libvirtaio.py', 'build')
 
         build.run(self)