RFR: 8287903: Reduce runtime of java.math microbenchmarks

[Claes Redestad]

- Reduce runtime by running fewer forks, fewer iterations, less warmup. All micros tested in this group appear to stabilize very quickly.
- Refactor BigIntegers to avoid re-running some (most) micros over and over with parameter values that don't affect them.

Expected runtime down from 14 hours to 15 minutes.

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Commit messages:
 - Cleanup SmallShifts, reduce param space
 - Annotations not cascading to static nested class
 - Warmup/Measurement not cascading to static nested class
 - Reduce runtime of java.math micros
 - Reduce runtime of java.math micros

Changes: https://git.openjdk.java.net/jdk/pull/9062/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=9062&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8287903
  Stats: 104 lines in 4 files changed: 66 ins; 33 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/9062.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/9062/head:pull/9062

PR: https://git.openjdk.java.net/jdk/pull/9062