RFR: 8268289: build failure due to missing signed flag in x86 evcmpb instruction

[Jatin Bhateja]

Code introduced with PR/3999

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Commit messages:
 - 8268289: build failure due to missing signed flag in x86 evcmpb instruction

Changes: https://git.openjdk.java.net/jdk/pull/4375/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4375&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268289
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4375.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4375/head:pull/4375

PR: https://git.openjdk.java.net/jdk/pull/4375