[jdk11u-dev] RFR: 8307955: Prefer to PTRACE_GETREGSET instead of PTRACE_GETREGS in method 'ps_proc.c::process_get_lwp_regs'

[Gui Cao]

Hi, This is also needed for riscv-port-jdk11u repo where we have full-reatured linux-riscv port for the same reason as jdk17u backport. The backport is not clean because the sparc architecture related code still exists. Risk is low as this is a small change prefering using `PTRACE_GETREGSET` instead of `PTRACE_GETREGS`. Tested on linux-aarch64 and linux-x86_64 platforms.

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Commit messages:
 - Backport8307955: Prefer to PTRACE_GETREGSET instead of PTRACE_GETREGS in method 'ps_proc.c::process_get_lwp_regs'

Changes: https://git.openjdk.org/jdk11u-dev/pull/2549/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2549&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307955
  Stats: 13 lines in 1 file changed: 6 ins; 6 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2549.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2549/head:pull/2549

PR: https://git.openjdk.org/jdk11u-dev/pull/2549