RFR: 8305055: IR check fails on some aarch64 platforms [v2]

[Fei Gao]

> As @eme64 said in [1], [JDK-8298935](https://bugs.openjdk.org/browse/JDK-8298935) introduced some "collateral damage", disabling the vectorization of some conversions when `+AlignVector`. That affects IR checks of `TestVectorizeTypeConversion.java` and `ArrayTypeConvertTest.java` on some `aarch64` platforms like ThunderX and ThunderX2 [2].
> 
> This trivial patch is to allow IR check only when we have `-AlignVector`.
> 
> [1] https://github.com/openjdk/jdk/pull/12350#issuecomment-1470065706
> [2] https://github.com/openjdk/jdk/blob/7239150f8aff0e3dc07c5b27f6b7fb07237bfc55/src/hotspot/cpu/aarch64/vm_version_aarch64.cpp#L154

Fei Gao has updated the pull request incrementally with one additional commit since the last revision:

  Update comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13236/files
  - new: https://git.openjdk.org/jdk/pull/13236/files/78fcd6e5..04f8b116

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13236&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13236&range=00-01

  Stats: 8 lines in 2 files changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/13236.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13236/head:pull/13236

PR: https://git.openjdk.org/jdk/pull/13236