Fix XmlPatch attribute selector matching on intermediate nodes

[dejlek]

The selAttrId was incorrectly checked on all nodes in the selector path instead of only the final target node, causing rename attribute operations with multi-level selectors to fail.

If we leave the unittest without these changes we get:

xml_patch.XmlPatchError@source/xml_patch.d(469): XML patch selector 'root.child[test]' did not match
----------------
??:? _d_createTrace [0x7fdac3933acf]
??:? _d_throw [0x7fdac3926f90]
source/xml_patch.d:247 void xml_patch.XmlPatch.apply(xml_tree.XmlTree, xml_tree.XmlNode) [0x415b48]
source/xml_patch.d:482 void xml_patch.__unittest_L473_C1() [0x6005a3]
source/xml_patch.d:484 void xml_patch.__modtest() [0x6005bb]