[jdk17u] RFR: 8271862: C2 intrinsic for Reference.refersTo() is often not used

[Aleksey Shipilev]

Clean backport to make JDK 16 introduced feature more compelling with a workaround.

Additional testing:
 - [x] Linux x86_64 fastdebug, `RefersTo` tests pass

`RefersTo` tests:


./test/hotspot/jtreg/gc/TestReferenceRefersTo.java
./test/hotspot/jtreg/gc/TestReferenceRefersToDuringConcMark.java
./test/hotspot/jtreg/gc/shenandoah/TestReferenceRefersToShenandoah.java
./test/hotspot/jtreg/compiler/intrinsics/TestReferenceRefersTo.java
./test/jdk/java/lang/ref/ReferenceRefersTo.java

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Commit messages:
 - Backport 3f723ca4577b9cffeb6153ee386edd75f1dfb1c6

Changes: https://git.openjdk.java.net/jdk17u/pull/62/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=62&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271862
  Stats: 14 lines in 2 files changed: 11 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/62.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/62/head:pull/62

PR: https://git.openjdk.java.net/jdk17u/pull/62