Issue #18256: Compilation fix for recent AIX releases. Patch by David Edelsohn.

Misc/ACKS

@@ -270,6 +270,7 @@ Josip Dzolonga
 Maxim Dzumanenko
 Walter Dörwald
 Hans Eckardt
+David Edelsohn
 Grant Edwards
 John Ehresman
 Eric Eisner

Misc/NEWS

@@ -49,6 +49,9 @@ Library
 Build
 -----
 
+- Issue #18256: Compilation fix for recent AIX releases.  Patch by
+  David Edelsohn.
+
 - Issue #18098: The deprecated OS X Build Applet.app fails to build on
   OS X 10.8 systems because the Apple-deprecated QuickDraw headers have
   been removed from Xcode 4.  Skip building it in this case.

Python/thread_pthread.h

@@ -145,6 +145,7 @@ static void
 PyThread__init_thread(void)
 {
 #if defined(_AIX) && defined(__GNUC__)
+    extern void pthread_init(void);
     pthread_init();
 #endif
 }
@@ -394,6 +395,7 @@ PyThread_free_lock(PyThread_type_lock lock)
     pthread_lock *thelock = (pthread_lock *)lock;
     int status, error = 0;
 
+    (void) error; /* silence unused-but-set-variable warning */
     dprintf(("PyThread_free_lock(%p) called\n", lock));
 
     status = pthread_mutex_destroy( &thelock->mut );
@@ -445,6 +447,7 @@ PyThread_release_lock(PyThread_type_lock lock)
     pthread_lock *thelock = (pthread_lock *)lock;
     int status, error = 0;
 
+    (void) error; /* silence unused-but-set-variable warning */
     dprintf(("PyThread_release_lock(%p) called\n", lock));
 
     status = pthread_mutex_lock( &thelock->mut );