DO NOT MERGE: Heap buffer overflow in xmlAddID

Patch from ddkilzer@apple.com
See https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=598
and https://bugzilla.gnome.org/show_bug.cgi?id=780228

Bug: 37104170
Change-Id: I0286459ff9066b664dc26f7f1ff65a1388de3d92
1 file changed