xmlSnprintfElementContent failed to correctly check the available
buffer space in two locations.
Fixes bug 781333 and bug 781701
CVE: CVE-2017-9047 CVE-2017-9048
(From OE-Core rev: bb0af023e811907b4e641b39f654ca921ac8794a)
Signed-off-by: Andrej Valek <andrej.valek@siemens.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>