Fixes two CVEs:
- CVE-2019-15903 (Fix heap overflow triggered by XML_GetCurrentLineNumber)
- CVE-2018-20843 (Fix extraction of namespace prefixes from XML names)
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
(cherry picked from commit b4af2c689fc8736777940b7bbf009bb1672296ec)