Following the availability of apr_hash_this_key() etc. in APR v1.5, use these in Subversion code instead of svn__apr_hash_index_key() etc. Provide substitutes only when APR is too old to provide them.
* subversion/include/svn_types.h, subversion/libsvn_subr/iter.c (svn__apr_hash_index_key, svn__apr_hash_index_klen, svn__apr_hash_index_val): Rename to apr_hash_this_key, apr_hash_this_key_len, apr_hash_this_val. Declare and define them only if APR is older than 1.5.
Revert r1508225, which moved the include of svn_private_config.h before all includes of our public headers. Public headers shouldn't depend on private headers and all changes that required this are long reverted on trunk.