[8u40] 8042195, 8042737 : Introduce umbrella header

[Vladimir Kozlov]

8u40 backport request. Fixes were pushed into jdk9 2 months ago and 
nightly testing shows no problems.

8042195: Introduce umbrella header orderAccess.inline.hpp.
8042737: Introduce umbrella header prefetch.inline.hpp

Changes (including closed) from jdk9 applied to 8u without conflicts. I 
also ran JPRT test job to verify backport.

http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/2377269bd73d
http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/4cc7fe54e0e1

https://bugs.openjdk.java.net/browse/JDK-8042195
https://bugs.openjdk.java.net/browse/JDK-8042737

Thanks,
Vladimir