RFR: 8330156: RISC-V: Range check auipc + signed 12 imm instruction

[Robbin Ehn]

Hi please consider!

Today we check if the distance is a signed 32.
As the second instruction have sign bit + 11 bits the, max of such pair is shorter.

Sanity tested

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Commit messages:
 - Check true range

Changes: https://git.openjdk.org/jdk/pull/18755/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18755&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330156
  Stats: 11 lines in 2 files changed: 6 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/18755.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18755/head:pull/18755

PR: https://git.openjdk.org/jdk/pull/18755