fix: yajl detection for source installations (#3457)

[weida]

what

• Modified find_yajl.m4 to correctly detect yajl when installed from source.
• Added a check for the lib subdirectory in addition to the top-level path.
• Ensures that ModSecurity compilation succeeds when --with-yajl is specified.

why

• The build failed to detect yajl 2.1.0 compiled from source, even when the correct path was provided.

references

• Issue: ModSecurity v2.9.12: find_yajl.m4 fails to detect YAJL installed from source #3457

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[airween]

Thanks for your patch, @weida!