let --disable-external-python work with --enable-external-libraries

--- a/configure.in
+++ b/configure.in
@@ -235,7 +235,7 @@
             [AS_HELP_STRING([--enable-external-python],
             [enable use of external python library (default is no) 'Linux only'])],
             [use_external_python=$enableval],
-            [use_external_python=no])
+            [use_external_python=$use_external_libraries])
 
 ### End of external library options
 
@@ -620,7 +620,7 @@
 fi
 
 # External Python
-if test "$use_external_libraries" = "yes" || test "$use_external_python" = "yes"; then
+if test "$use_external_python" = "yes"; then
   AC_CHECK_LIB([python2.6], [main],,
   [AC_CHECK_LIB([python2.5], [main],,
   [AC_CHECK_LIB([python2.4], [main],,