[jdk19u] RFR: 8295264: Fix PaX check on RISC-V

[Ludovic Henry]

On Linux RISC-V, PROT_WRITE doesn't imply PROT_READ [1]

The fix is to pass PROT_READ|PROT_WRITE. That matches all other calls to mmap in hotspot.

[1] https://lkml.org/lkml/2022/9/8/1066

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Commit messages:
 - Backport 4434cbb719db37880b48474ba342f300ed4828a8

Changes: https://git.openjdk.org/jdk19u/pull/91/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk19u&pr=91&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295264
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk19u/pull/91.diff
  Fetch: git fetch https://git.openjdk.org/jdk19u pull/91/head:pull/91

PR: https://git.openjdk.org/jdk19u/pull/91