RFR: 8175385: ServiceLoader$LazyClassPathLookupIterator scans boot and platform modules for services

[Claes Redestad]

Hi,

related to the same regression as JDK-8175561, there are now some cases
where we unnecessarily scan platform modules for services.  This patch
allows us to skip the platform and boot classloaders in certain cases,
which speeds up loading and enumerating the built-in services.

Bug: https://bugs.openjdk.java.net/browse/JDK-8175561
Webrev: http://cr.openjdk.java.net/~redestad/8175385/jdk.01/

Thanks!

/Claes