[libxml2] Restore behavior of --with-threads without argument

[Daniel Veillard <veillard src gnome org>]

commit 2bdf87e3444090414e9ae7f90e4ef9085963eb39
Author: Andrew W. Nosenko <andrew w nosenko gmail com>
Date:   Thu Sep 24 17:33:21 2009 +0200

    Restore behavior of --with-threads without argument
    
    * configure.in: restore behavior of --with-threads without argument as
      "enable threads support"

 configure.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.in b/configure.in
index 90d8b73..811cd45 100644
--- a/configure.in
+++ b/configure.in
@@ -886,7 +886,7 @@ if test "$with_threads" = "no" ; then
 else
     echo Enabling multithreaded support
     dnl Use pthread by default
-    if test "$with_threads" = "pthread" | test "$with_threads" = "" ; then
+    if test "$with_threads" = "pthread" | test "$with_threads" = "" | test "$with_threads" = "yes" ; then
         AC_CHECK_HEADER(pthread.h,
 	    AC_CHECK_LIB(pthread, pthread_join,[
 	       THREAD_LIBS="-lpthread"