std::size/SAL_N_ELEMENTS also counts the null terminator
which libxml2 2.12 will fail on with error:
'Extra content at the end of the document'
Change-Id: I9d5da9fdd826cce8462ede8c510eaea7281b760f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/161627
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>
(cherry picked from commit
cbb17a548b5cc6a99b6ed7735479bb4f2bc40f26)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/161643
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>