Let user to explicit disable libnss and libnspr support
Since libnss and libnspr are not mandatory, there is an option on FreeBSD ports tree to let user to chose to disable it during build phase.
It works as expected when building binary packages on a clean environment. When user build the port locally and has one of these libraries installed in the system, if it choses to disable them, configure script doesn't provide a explicit option to have it disabled and then binary package ends up broken because it has binaries linked against these libraries but doesn't have the correct dependency registered to make sure nss/nspr are installed on the system.
It would be good to provide configure options to let user to explicit chose to don't use these libraries.