RFR: 8322816: RISC-V: Incorrect guarantee in patch_vtype

[Kim Barrett]

Please review this change that fixes a test for a guarantee.  This also
removes a -Wparentheses warning when those are enabled (which is how the
problem was discovered).

The problem is that operator precedence groups the sub-expressions differently
than intended. The fix is to override the operator precedence by adding
parentheses to achieve the intended grouping.

Testing: Local (linux-x64) cross-build for linux-riscv with this change plus
-Wparentheses enabled and other changes to allow that to work.

Requesting someone from the riscv porters to properly test this.

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Commit messages:
 - fix subexpression grouping in patch_vtype guarantee

Changes: https://git.openjdk.org/jdk/pull/17215/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17215&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322816
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/17215.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17215/head:pull/17215

PR: https://git.openjdk.org/jdk/pull/17215