Allow length 0 in arrayTranslateTRTO for Power

[knn-k]

This commit changes arrayTranslateTRTO helper function for Power to handle the case of length zero.

[knn-k]

__arrayTranslateTRTO branches to .L.__alignResidue_TRTO when the length is shorter than 8 or 23 (depending on ALIGNLOOP). This commit adds a check for the case of length zero to .L.__alignResidue_TRTO so that the caller side can stop checking the case before calling the helper function.
All other three arraytranslate helper functions accept zero as the length.

[knn-k]

Jenkins test sanity plinux,aix jdk17 depends eclipse-omr/omr#7649

[knn-k]

Jenkins test sanity.openjdk aix jdk17 depends eclipse-omr/omr#7649

Re-running as the previous job failed due to an infrastructure problem.

[2025-02-10T04:15:22.440Z] XML output with verification to /home/jenkins/workspace/Test_openjdk17_j9_sanity.openjdk_ppc64_aix_Personal_testList_2/aqa-tests/TKG/output_17391559119732/jdk_security2_1/work
[2025-02-10T04:27:19.884Z] Cannot contact p8-java1-ibm10: java.lang.InterruptedException

[knn-k]

Jenkins test sanity.openjdk aix jdk17 depends eclipse-omr/omr#7649

[knn-k]

sanity.functional contains a test for arraytranslateTRTO in https://github.com/eclipse-openj9/openj9/blob/master/test/functional/JIT_Test/src/jit/test/tr/arrayTranslate/ArrayTranslateTest.java, and the test checks the case of length zero.

There are some failures with javax/crypto on AIX: See #19962

[knn-k]

A PR in OMR stops checking the length in the caller side.

[knn-k]

@zl-wang FYI.

[zl-wang]

don't you need to handle zero element in all 4 helpers? i only saw it is handled in one.

[knn-k]

It is safe to pass zero as the length to the other three helper functions.
arrayTranslateTRTO is the only helper that doesn't accept zero length.

[zl-wang]

ok then.