contribs: unbreak libxml compilation on Darwin

contrib/src/libxml2/osx-threads.patch

---- libxml2-2.9.0/threads.c.orig	2012-11-10 08:11:05.000000000 -0500
-+++ libxml2-2.9.0/threads.c	2012-11-10 08:12:30.000000000 -0500
-@@ -146,6 +146,7 @@
- static pthread_key_t globalkey;
- static pthread_t mainthread;
- static pthread_once_t once_control = PTHREAD_ONCE_INIT;
-+static pthread_once_t once_control_init = PTHREAD_ONCE_INIT;
- static pthread_mutex_t global_init_lock = PTHREAD_MUTEX_INITIALIZER;
- #elif defined HAVE_WIN32_THREADS
- #if defined(HAVE_COMPILER_TLS)
-@@ -915,7 +916,7 @@
- #ifdef HAVE_PTHREAD_H
-     if ((libxml_is_threaded)  && (pthread_key_delete != NULL))
-         pthread_key_delete(globalkey);
--    once_control = PTHREAD_ONCE_INIT;
-+    once_control = once_control_init;
- #elif defined(HAVE_WIN32_THREADS) && !defined(HAVE_COMPILER_TLS) && (!defined(LIBXML_STATIC) || defined(LIBXML_STATIC_FOR_DLL))
-     if (globalkey != TLS_OUT_OF_INDEXES) {
-         xmlGlobalStateCleanupHelperParams *p;

contrib/src/libxml2/rules.mak

@@ -17,9 +17,6 @@ XMLCONF = --with-minimal --with-catalog --with-reader --with-tree --with-push --
 
 libxml2: libxml2-$(LIBXML2_VERSION).tar.gz .sum-libxml2
 	$(UNPACK)
-ifdef HAVE_DARWIN_OS
-	$(APPLY) $(SRC)/libxml2/osx-threads.patch
-endif
 	$(APPLY) $(SRC)/libxml2/no-tests.patch
 	$(APPLY) $(SRC)/libxml2/win32.patch
 	$(APPLY) $(SRC)/libxml2/pthread.patch