This is the last 60-esr I believe.
- fixed multiple outputs (saves $out 2MB from $out)
- updated the only patch we carry
- symlinked `js` to `js60`, some packages using spidermonkey expects `js`. Might
make it possible to drop 38 in the future.
This is essentially the same as done in
65f2b0a2a3.
For spidermonkey_38 I set --enable-posix-nspr-emulation, as it would
otherwise complain about a wrong NSPR version and that trick seemed to
be successful in spidermonkey_60 anyway.
