RFR: 8292385: assert(ctrl == kit.control()) failed: Control flow was added although the intrinsic bailed out

[Dean Long]

The problem is caused by missing bailout logic in inline_string_char_access().  This PR adds the needed logic to match other intrinsics.

I tried to come up with a stand-alone test case, but was not successful.

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Commit messages:
 - add standard bailout logic to inline_string_char_access

Changes: https://git.openjdk.org/jdk/pull/10136/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10136&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292385
  Stats: 7 lines in 1 file changed: 7 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10136.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10136/head:pull/10136

PR: https://git.openjdk.org/jdk/pull/10136