Added optimized memmem/strlcpy version

[utoni]

• credits goes to Vladimir Gavrilov

Please sign (check) the below before submitting the Pull Request:

• I have signed the ntop Contributor License Agreement at https://github.com/ntop/legal/blob/main/individual-contributor-licence-agreement.md
• I have read the contributing guide lines at https://github.com/ntop/nDPI/blob/dev/CONTRIBUTING.md
• I have updated the documentation (in doc/) to reflect the changes made (if applicable)

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[IvanNardi]

@utoni, how did you recover this code?

[utoni]

Vladimir sent it to me :)