libmaxminddb: improper initialization in dump_entry_data_list() in maxminddb.c (CVE-2020-28241)

libmaxminddb before 1.4.3 has a heap-based buffer over-read in dump_entry_data_list in maxminddb.c.

References:

• https://github.com/maxmind/libmaxminddb/issues/236
• https://nvd.nist.gov/vuln/detail/CVE-2020-28241
• https://github.com/maxmind/libmaxminddb/pull/237

Affected branches:

• master (39c5a644)
• 3.12-stable
• 3.11-stable
• 3.10-stable