RFR: 8254785: compiler/graalunit/HotspotTest.java failed with "missing Graal intrinsics for: java/lang/StringLatin1.indexOfChar([BIII)I"

[Aleksey Shipilev]

This test is problem-listed, and thus misses new intrinsics completely. The new `StringLatin1.indexOf` intrinsic can
just be added to `toBeInvestigated` list in `CheckGraalIntrinsics.java`, instead of problem-listing the entire test and
thus missing even more intrinsics.

Testing:
  - [x] Linux x86_64 `compiler/graalunit` tests

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

Commit messages:
 - 8254785: compiler/graalunit/HotspotTest.java failed with "missing Graal intrinsics for: java/lang/StringLatin1.indexOfChar([BIII)I"

Changes: https://git.openjdk.java.net/jdk/pull/762/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=762&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254785
  Stats: 8 lines in 2 files changed: 7 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/762.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/762/head:pull/762

PR: https://git.openjdk.java.net/jdk/pull/762