autotools: Set AC_CONFIG_AUX_DIR

This should make sure that autoreconf doesn't mess with parent
directories.

Should fix #833.

Author: nwellnhof

configure.ac

@@ -9,6 +9,7 @@ AC_INIT([libxml2],[MAJOR_VERSION.MINOR_VERSION.MICRO_VERSION])
 AC_CONFIG_SRCDIR([entities.c])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_MACRO_DIR([m4])
+AC_CONFIG_AUX_DIR([.])
 AC_CANONICAL_HOST
 
 LIBXML_MAJOR_VERSION=MAJOR_VERSION