RFR: 8267773: PhaseStringOpts::int_stringSize doesn't handle min_jint correctly

[Nils Eliasson]

Hi,

PhaseStringOpts::int_stringSize doesn't handle min_jint correctly - it can't be negated to a positive number. I fix this adding a special case for this.

Added a test that was contributed by Adam who reported the bug. Will add as a contributor.

Please review,
Best regards,
Nils Eliasson

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Commit messages:
 - Fix overflow in strconcat

Changes: https://git.openjdk.java.net/jdk/pull/4255/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4255&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267773
  Stats: 75 lines in 2 files changed: 75 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4255.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4255/head:pull/4255

PR: https://git.openjdk.java.net/jdk/pull/4255