tdf#42949 Fix IWYU warnings in xmlreader/

Found with bin/find-unneeded-includes
Only removal proposals are dealt with here.

Change-Id: I9e64ad0a20654e2b97de5b23302ce2cab1a09c00
Reviewed-on: https://gerrit.libreoffice.org/66975
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>

xmlreader/IwyuFilter_xmlreader.yaml

+---
+assumeFilename: xmlreader/source/xmlreader.cxx

xmlreader/source/span.cxx

@@ -22,7 +22,6 @@
 #include <cassert>
 
 #include <com/sun/star/uno/RuntimeException.hpp>
-#include <com/sun/star/uno/XInterface.hpp>
 #include <rtl/textcvt.h>
 #include <rtl/textenc.h>
 #include <rtl/ustring.h>

xmlreader/source/xmlreader.cxx

@@ -21,11 +21,9 @@
 
 #include <cassert>
 #include <climits>
-#include <cstddef>
 
 #include <com/sun/star/container/NoSuchElementException.hpp>
 #include <com/sun/star/uno/RuntimeException.hpp>
-#include <com/sun/star/uno/XInterface.hpp>
 #include <osl/file.h>
 #include <rtl/character.hxx>
 #include <rtl/string.h>