javac option listing is broken for ONEOF option types

The entire list of options is printed when each individual option should be printed.

  -Xprefer:{[source, newer],[source, newer]}
        Specify which file to read when both a source file and class file are found for an implicitly compiled class

  -Xpkginfo:{[always, legacy, nonempty],[always, legacy, nonempty],[always, legacy, nonempty]}
        Specify handling of package-info files