XPath: Replace all (re)allocate_throw with (re)allocate_nothrow
XPath: Replace all (re)allocate_throw with (re)allocate_nothrow

This generates some out-of-memory code paths that are not covered by
existing tests, which will need to be resolved later.

zeux/pugixml,zeux/pugixml,zeux/pugixml,zeux/pugixml