Add javadoc command line setting to fail on warnings

A DESCRIPTION OF THE REQUEST :
javadoc is able to emit certain warnings like a missing description for a parameter. It would be great if there were a switch which would make javadoc to bail out on those warnings with an error return code. Like -Werror does for common compilers.

JUSTIFICATION :
This is an often requested feature. See for example

- https://stackoverflow.com/questions/8392559/javadoc-treat-warnings-as-errors
- https://discuss.gradle.org/t/javadoc-fail-on-warning/18141
- https://stackoverflow.com/questions/29519085/how-to-fail-gradle-build-on-javadoc-warnings/33153700

Currently the only solution is to restort to quick hacks, like scanning the javadoc output for warnings. Native support for this in javadoc would make those hacks unnecessary and hence seems desirable.