Coverity

[rlm2002]

Description

560796: Dereference before null check - remove check as extension->data would not be NULL at this point
560760: Logically dead code - remove dead length check
560126: Dereference after null check - introduce defaultSz variable to handle s == NULL
560794: Dereference after null check - remove check as ssl->ctx and ssl->ctx->method would not be NULL in normal operation at this point

Also adds unit test for NULL parameters in EVP_DigestFinal() with SHAKE

Testing

./configure --enable-all && make check

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation