RFR(s): 8197992: Move the OopStorage::ParState type out of inline.hpp

[Per Liden]

Please view this patch, which moves the OopStorage::ParState type out 
from oopStorageParState.inline.hpp and into a new 
oopStorageParState.hpp. The functions depending on other .inline.hpp 
includes remain in oopStorageParState.inline.hpp.

This patch is needed to allow classes defined in other .hpp files to 
contain a oopStorage::ParState instance by value (without having 
inline.hpp includes in .hpp file). ZGC's ZRootIterator is an example of 
this.

Bug: https://bugs.openjdk.java.net/browse/JDK-8197992
Webrev: http://cr.openjdk.java.net/~pliden/8197992/webrev.0/
Testing: hs-tier1

/Per