Fixed logically dead code

[soumyajit11]

CID 1508856: Logically dead code #10432

In access_control.cc:

197    size_t equalsign = kvp.find(_tokenConfig.kvDelimiter);
   	cond_cannot_single: Condition 18446744073709551615UL == equalsign, taking false branch. Now the value of equalsign cannot be equal to -1.
198    if (kvp.npos == equalsign) {
199      ERROR_OUT("invalid key-value-pair, missing key-value delimiter");
200      return _state = INVALID_SYNTAX;
201    }
202    StringView key   = kvp.substr(0, equalsign);
   	cannot_single: At condition equalsign != 18446744073709551615UL, the value of equalsign cannot be equal to -1.
   	dead_error_condition: The condition equalsign != 18446744073709551615UL must be true.

CID 1508856 (#1 of 1): Logically dead code (DEADCODE)
dead_error_line: Execution cannot reach this statement: <temporary>.basic_string_vi....
203    StringView value = equalsign != kvp.npos ? kvp.substr(equalsign + 1) : "";

[JosiahWI]

Thank you for fixing the code! I checked and this fix is also correct when '=' is the very last character in the view.
Edit: this code has good unit test coverage as well.

[bneradt]

@soumyajit11 : @JosiahWI pointed out that your osx build should work once you rebase on top of latest master to pull in a fix for including openssl. Can you please rebase and push again? I'm guessing the autest failure is spurious and will pass when you re-run CI via your push.