RFR: 8254855: Clean up and remove unused code in vmIntrinsics

[Claes Redestad]

- Remove unused code and constants
- Guard some code only used for assertions by ASSERT
- Adjust log2_FLAG_LIMIT (could have been 3 also before removing F_RNY)

Testing: tier1-3

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Commit messages:
 - Merge branch 'master' into vmintrinsic_cleanup
 - vmIntrinsics.cpp: intrinsic_info can also be ASSERT-only
 - explicit endif
 - Clean-up and remove dead code from vmIntrinsics

Changes: https://git.openjdk.java.net/jdk/pull/688/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=688&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254855
  Stats: 124 lines in 2 files changed: 2 ins; 119 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/688.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/688/head:pull/688

PR: https://git.openjdk.java.net/jdk/pull/688