Release v1.5.1 on 2021-02-24.

1. 3da7938 Embedded: add sercomm stubs by Max · 6 years ago
2. a6a40dc Embedded: fix sercomm test by Max · 7 years ago
3. fe1ed398 sercomm_test: sanitize: fix msgb mem leak by Neels Hofmeyr · 7 years ago
4. fc1911c sercomm_test.c: return correctly in main by Pau Espin Pedrol · 7 years ago
5. a362ee9 add sercomm unit test by Harald Welte · 7 years ago