Treat loop in xref tables as damage (fixes #192)

Prior to this fix, if there was a loop detected in following /Prev
pointers in xref streams/tables, it would cause qpdf to lose data.
Note that this condition causes many PDF readers to hang or fail.

1 files changed, 5 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index e7a32833..bba500ee 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-03-05  Jay Berkenbilt  <ejb@ql.org>
+
+	* Improve handling of loops while following cross reference
+	tables. Fixes #192.
+
 2018-03-04  Jay Berkenbilt  <ejb@ql.org>
 
 	* 8.0.1: release