RFR: 8369080: Use uname -m for devkit cpu detection

[Mikael Vidstedt]

The devkit creation uses uname -p for detection the cpu architecture. uname -p is non-portable and no longer works on recent Linux/distributions (e.g. OL10). It should be changed to uname -m which is portable and works.

Testing: manual verification on ol{7,8,9,10}-{aarch64,x86_64}

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Commit messages:
 - 8369080: Use uname -m for devkit cpu detection

Changes: https://git.openjdk.org/jdk/pull/27617/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27617&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8369080
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/27617.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27617/head:pull/27617

PR: https://git.openjdk.org/jdk/pull/27617