Prefer python2 binary in case python points to python3

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>

diff -uNr libxml2-2.9.1.org/configure.in libxml2-2.9.1/configure.in
--- libxml2-2.9.1.org/configure.in	2013-04-19 09:25:20.000000000 +0200
+++ libxml2-2.9.1/configure.in	2014-04-12 14:16:26.579361068 +0200
@@ -748,6 +748,11 @@
 PYTHON_TESTS=
 pythondir=
 if test "$with_python" != "no" ; then
+    if test -x "$with_python/bin/python2"
+    then
+        echo Found python2 in $with_python/bin/python2
+        PYTHON="$with_python/bin/python2"
+    else
     if test -x "$with_python/bin/python"
     then
         echo Found python in $with_python/bin/python
@@ -773,6 +778,7 @@
 	    fi
 	fi
     fi
+    fi
     if test "$PYTHON" != ""
     then
         PYTHON_VERSION=`$PYTHON -c "from distutils import sysconfig; print(sysconfig.get_python_version())"`