libubox: update to version 2020-01-20

libubox: update to version 2020-01-20

 43a103ff17ee blobmsg: blobmsg_parse and blobmsg_parse_array oob read fixes
 5c0faaf4f5e2 tests: prefer dynamically allocated buffers
 1ffa41535369 blobmsg_json: prefer snprintf usage
 132ecb563da7 blobmsg: blobmsg_vprintf: prefer vsnprintf
 a2aab30fc918 jshn: prefer snprintf usage
 b0886a37f39a cmake: add a possibility to set library version
 a36ee96618a9 blobmsg: blobmsg_add_json_element() 64-bit values
 f0da3a4283b7 blobmsg_json: fix int16 serialization
 20a070f08139 tests: blobmsg/json: add more test cases
 379cd33d1992 tests: include json script shunit2 based testing

Acked-by: Jo-Philipp Wich <jo@mein.io>
Signed-off-by: Petr Štetiar <ynezz@true.cz>
(cherry picked from commit 5c73bb12c82c078d8a93cb896348b41598ed9e19)