this patch is now in classpath trunk. the compiler does accept the newer -source
versions, so gjdoc should do as well (with a warning).

ok for the trunk?
ok for the 4.7 branch as well? it looks safe, as it only tries to accept the
option, and maybe bails out later. at least it helps with unmodified sources
which are now built with a newer -source option.

  Matthias