libubox: update to version 2019-12-28

libubox: update to version 2019-12-28

Contains following changes:

 cd75136b1342 blobmsg: fix wrong payload len passed from blobmsg_check_array
 eb7eb6393d47 blobmsg: fix array out of bounds GCC 10 warning
 86f6a5b8d1f1 blobmsg: reuse blobmsg_namelen in blobmsg_data
 586ce031eaa0 tests: fuzz: fuzz _len variants of checking methods
 b0e21553ae8c blobmsg: add _len variants for all attribute checking methods
 cd3059796a57 Replace use of blobmsg_check_attr by blobmsg_check_attr_len
 143303149c8b Ensure blob_attr length check does not perform out of bounds reads
 f2b2ee441adb blobmsg: fix heap buffer overflow in blobmsg_parse
 4dfd24ed88c4 blobmsg: make blobmsg_len and blobmsg_data_len return unsigned value
 2df6d35e3299 tests: add test cases for blobmsg parsing
 8a34788b46c4 test: fuzz: add blobmsg_check_attr crashes
 478597b9f9ae blob: fix OOB access in blob_check_type
 325418a7a3c0 tests: use blob_parse_untrusted variant
 0b24e24b93e1 blob: introduce blob_parse_untrusted
 6d27336e4a8b blob: refactor attr parsing into separate function
 833d25797b16 test: fuzz: add blob_parse crashes
 09ee90f8d6ed tests: add test cases for blob parsing
 436d6363a10b tests: add libFuzzer based tests
 bf680707acfd tests: add unit tests covered with Clang sanitizers
 f804578847de cmake: add more hardening compiler flags
 46f8268b4b5b blobmsg/ulog: fix format string compiler warnings
 eb216a952407 cmake: use extra compiler warnings only on gcc6+
 07413cce72e1 tests: jshn: add more test cases
 26586dae43a8 jshn: fix missing usage for -p and -o arguments
 8e832a771d3a jshn: fix off by one in jshn_parse_file
 cb698e35409b jshn: jshn_parse: fix leaks of memory pointed to by 'obj'
 c42f11cc7c0f jshn: main: fix leak of memory pointed to by 'vars'
 93848ec96dc5 jshn: refactor main into smaller pieces
 9b6ede0e5312 avl: guard against theoretical null pointer dereference
 c008294a8323 blobmsg_json: fix possible uninitialized struct member
 0003ea9c45cc base64: fix possible null pointer dereference
 8baeeea1f52d add assert.h component
 b0a5cd8a28bf add cram based unit tests
 1fefb7c4d7f9 add initial GitLab CI support
 c955464d7a9b enable extra compiler checks
 6228df9de91d iron out all extra compiler warnings

and bumps ABI_VERSION to 20191228.

Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Petr Štetiar <ynezz@true.cz>