[AArch64][SVE] Fix hang in VECTOR_HISTOGRAM DAG combine (#152539)

The histogram DAG combine went into an infinite loop of creating the
same histogram node due to an incorrect use of the `refineUniformBase`
and `refineIndexType` APIs.

These APIs take SDValues by reference (SDValue&) and return `true` if
they were "refined" (i.e., set to new values).

Previously, this DAG combine would create the `Ops` array (used to
create the new histogram node) before calling the `refine*` APIs, which
copies the SDValues into the array, meaning the updated values were not
used to create the new histogram node.

Reproducer: https://godbolt.org/z/hsGWhTaqY (it will timeout)

0 files changed, 0 insertions, 0 deletions