RFR: 8297417: Poly1305IntrinsicFuzzTest fails with tag mismatch exception

[Volodymyr Paprotski]

>From https://github.com/openjdk/jdk/pull/10582, `t0` gets clobbered if `rscratch` is used. Example, [here](https://github.com/openjdk/jdk/blob/09f70dad2fe3f0691afacded6c38f61fa8a0d28d/src/hotspot/cpu/x86/stubGenerator_x86_64_poly.cpp#L605-L606): 


  __ mov(t0, a0);
  __ andq(t0, ExternalAddress(poly1305_mask44()), rscratch); // First limb (R^4[43:0])

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Commit messages:
 - fix t0 rscratch usage overlap

Changes: https://git.openjdk.org/jdk/pull/11308/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11308&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297417
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/11308.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11308/head:pull/11308

PR: https://git.openjdk.org/jdk/pull/11308