RFR: 8229186: Improve error messages for TestStringIntrinsics failures

[Evgeny Nikitin]

pre-Skara RFR thread: [link](https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2020-May/038416.html)

Error reporting was improved by writing a C-style escaped string representations for the variables passed to the
methods being tested. For array comparisons, a dedicated diff-formatter was implemented.

Sample output for comparing byte arrays (with artificial failure):
 ----------System.err:(21/1553)----------
 Result: (false) of 'arrayEqualsB' is not equal to expected (true)
 Arrays differ starting from [index: 7]:
 ... 5, 6,   7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, ...
 ... 5, 6, 125, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, ...
           ^^^^
 java.lang.RuntimeException: Result: (false) of 'arrayEqualsB' is not
 equal to expected (true)
          at
 compiler.intrinsics.string.TestStringIntrinsics.invokeAndCheckArrays(TestStringIntrinsics.java:273)
           at ... stack trace continues - E.N.
 Sample output for comparing char arrays:
 ----------System.err:(21/1579)*----------
 Result: (false) of 'arrayEqualsC' is not equal to expected (true)
 Arrays differ starting from [index: 7]:
 ... \\u0005, \\u0006, \\u0007, \\u0008, \\u0009, \\n, ...
 ... \\u0005, \\u0006,      }, \\u0008, \\u0009, \\n, ...
                     ^^^^^^^
 java.lang.RuntimeException: Result: (false) of 'arrayEqualsC' is not
 equal to expected (true)
          at
 compiler.intrinsics.string.TestStringIntrinsics.invokeAndCheckArrays(TestStringIntrinsics.java:280)
           at
 ... and so on - E.N.

testing: open/test/hotspot/jtreg/compiler/intrinsics/string/TestStringIntrinsics.java on linux, windows, macosx.

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

Commit messages:
 - 8229186: Improve error messages for TestStringIntrinsics failures

Changes: https://git.openjdk.java.net/jdk/pull/112/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=112&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8229186
  Stats: 1078 lines in 6 files changed: 1066 ins; 1 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/112.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/112/head:pull/112

PR: https://git.openjdk.java.net/jdk/pull/112