Updates security/modsecurity3 to version v3.0.3
We switch from using github directly to release tarballs to avoid issues when autoconf tries to get version numbers from git which is not necessarily available. This has already been correctly done for us with the release tar.
Also adds configure flags to be consistent with the build even in dirty environments where optional modules are installed (we might want to add options for these in the future, but I'm not sure how useful they are at the moment).
In addition we switch to using the install-strip target to satisfy poudriere testports desire for stripped binaries/libraries.