Issue #16537: Check whether self.extensions is empty in setup.py.

Patch by Jonathan Hosmer.
diff --git a/Misc/ACKS b/Misc/ACKS
index 1821682..f077ff7 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -588,6 +588,7 @@
 Nadav Horesh
 Alon Horev
 Jan Hosang
+Jonathan Hosmer
 Alan Hourihane
 Ken Howard
 Brad Howes
diff --git a/Misc/NEWS b/Misc/NEWS
index 0b8ba0c..5647504 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -15,6 +15,12 @@
 - Issue #22448: Improve canceled timer handles cleanup to prevent
   unbound memory usage. Patch by Joshua Moore-Oliva.
 
+Build
+-----
+
+- Issue #16537: Check whether self.extensions is empty in setup.py. Patch by
+  Jonathan Hosmer.
+
 
 What's New in Python 3.4.2?
 ===========================