8186738: (sl) ServiceLoader::stream doesn't update cache

[Alan Bateman]

There are are two issues in ServiceLoader that we crept in with re-write 
here in JDK 9. One is with the new stream method where the Provider 
elements are specified to be cached but the implementation dropped it in 
the final version. The second is specific to the security manager 
scenario where  errors encountered loading  or initializing providers (a 
static initializer throws an error for example) aren't wrapped with the 
ServiceConfigurationError.

The changes to address these issues are trivial and I'd like to get them 
fixed in jdk10/master:
    http://cr.openjdk.java.net/~alanb/8186738/webrev/index.html

-Alan