[jdk21u] RFR: 8315554: C1: Replace "cmp reg, 0" with "test reg, reg" on x86

[Aleksey Shipilev]

Clean backport to improve generated code density.

Additional testing:
 - [ ] Linux x86_64 fastdebug, `tier1 tier2 tier3 tier4`, `-XX:TieredStopAtLevel=1`

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Commit messages:
 - Backport bd477810b176696e0fd043f5594663ebcf9884cf

Changes: https://git.openjdk.org/jdk21u/pull/355/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=355&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315554
  Stats: 15 lines in 1 file changed: 5 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk21u/pull/355.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/355/head:pull/355

PR: https://git.openjdk.org/jdk21u/pull/355