wolfssl: update to v4.2.0-stable

wolfssl: update to v4.2.0-stable

Many bugs were fixed--2 patches removed here.

This release of wolfSSL includes fixes for 5 security vulnerabilities,
including two CVEs with high/critical base scores:

- potential invalid read with TLS 1.3 PSK, including session tickets
- potential hang with ocspstaping2 (always enabled in openwrt)
- CVE-2019-15651: 1-byte overread when decoding certificate extensions
- CVE-2019-16748: 1-byte overread when checking certificate signatures
- DSA attack to recover DSA private keys

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
(cherry picked from commit f4853f7cca816214cd6e64cffe2b73d0b8c16def)