In stamp always advance the pointer if *p= 0xef

The current implementation only advanced if 0xef is followed
by two non-zero bytes. In case of malformed input (0xef should be
the start byte of a three byte character) this leads to an infinite
loop. (CVE-2021-42260)

Issue: FP3-A11#414
Change-Id: Iacb92be1ebf4488fef4ad07cc98ed9d16c118989
Upstream: https://sourceforge.net/u/cvoegl/tinyxml/ci/f7ca0035d17a663f55668e662b840afce7b86112
(cherry picked from commit f7ca0035d17a663f55668e662b840afce7b86112)
1 file changed