[LoopVectorize] Move test from r246149 into a target-specific folder to appease bots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246154 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/LoopVectorize/reduction-small-size.ll b/test/Transforms/LoopVectorize/AArch64/reduction-small-size.ll
similarity index 100%
rename from test/Transforms/LoopVectorize/reduction-small-size.ll
rename to test/Transforms/LoopVectorize/AArch64/reduction-small-size.ll