Review for a fix in the launcher setting the bootclasspath for legacy mode

[Mandy Chung]

I fixed a bug in the launcher that allocates the buffer of an incorrect 
length for holding the bootclasspath VM option and also  clean up the 
wildcardModuleDirList function to use stack variables (vs using 
wildcardConcat whose return value should be freed).

Webrev:
    http://cr.openjdk.java.net/~mchung/jigsaw/launcher-fix/

Thanks
Mandy