How to import patch from jdk/jdk

[Laurent Bourgès]

Hi,

I tried to use hg qimport to backport the following jdk9 patch (png encoder
performance issue) on my local jdk8u:

https://bugs.openjdk.java.net/
<https://bugs.openjdk.java.net/browse/JDK-6488522>
browse/JDK-6488522 <https://bugs.openjdk.java.net/browse/JDK-6488522>

hg qpush fails as the patch class is in java.desktop module but jdk8 has no
module. It mentions the --prefix option.

What is the option or wiki page explaining how to use different prefixes ?

Thanks in advance,
Laurent