RFR: 8262950: Restructure compiler/intrinsics/TestRotate.java for easier compilation

[Aleksey Shipilev]

It seems that after [JDK-8256438](https://bugs.openjdk.java.net/browse/JDK-8256438) this test is very slow. See [JDK-8262465 ](https://bugs.openjdk.java.net/browse/JDK-8262465) for more evidence of this.
I believe the underlying cause is that `main()` is way too busy with test cases, so this eventually happens:

$ javac test/hotspot/jtreg/compiler/intrinsics/TestRotate.java
$ java -XX:-TieredCompilation -XX:CompileThreshold=1000 -Xbatch -XX:+PrintCompilation -cp test/hotspot/jtreg compiler.intrinsics.TestRotate
 ...
   6112 112 % !b compiler.intrinsics.TestRotate::main @ 1494 (3008 bytes) COMPILE SKIPPED: out of nodes during split (retry at different tier)

So, while the test is intended to test rotate intrinsics, I think it never gets there because compilation bails. And this also makes the test slow. This is tier1 test, and so its performance is somewhat important for developer experience.

This improvement restructures the test to be easier to JIT compile. This drops the test run time from ~4 minutes to ~20 seconds on my desktop. Plus, additional diagnostic flag verifies that compiler does not bail anywhere.

Attn @theRealELiu.

Additional testing:
  - [x] Linux x86_64 fastdebug, affected test
  - [x] Linux x86_64 release, affected test
  - [x] Linux aarch64 fastdebug, affected test

-------------

Commit messages:
 - Fix indents a bit
 - 8262950: Restructure compiler/intrinsics/TestRotate.java to run faster

Changes: https://git.openjdk.java.net/jdk/pull/2811/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2811&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262950
  Stats: 287 lines in 1 file changed: 172 ins; 3 del; 112 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2811.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2811/head:pull/2811

PR: https://git.openjdk.java.net/jdk/pull/2811