[8u40] RFR (XS) 8054376: Move RTM flags out from Experimental to Product

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/8054376_8u/webrev/
https://bugs.openjdk.java.net/browse/JDK-8054376

In JDK 8u20 RTM instructions and associated flags were added to Hotspot 
as experimental. For 8u40 we can move following flags to Product (as in 
jdk9): UseRTMLocking, UseRTMDeopt and RTMRetryCount.

We do regular testing of RTM in jdk 9 and did not find major problems.

This change is only for 8u because in jdk9 these flags are already product.

Thanks,
Vladimir