RFR: 8291048: x86: compiler/c2/irTests/TestAutoVectorization2DArray.java fails with lower SSE

[Aleksey Shipilev]

[JDK-8289801](https://bugs.openjdk.org/browse/JDK-8289801) whitelisted the UseSSE/UseAVX flags, but missed update in the test. So when we test x86_32 with lower SSE, it fails, as no `LoadVector`/etc nodes are getting emitted.

Additional testing: 
 - [x] Linux x86_32 fastdebug `c2/irTests` with `-XX:UseAVX=0 -XX:UseSSE=0` (now passes)
 - [x] Linux x86_32 fastdebug `c2/irTests` with `-XX:UseAVX=0 -XX:UseSSE=1` (now passes)
 - [x] Linux x86_32 fastdebug `c2/irTests` with `-XX:UseAVX=0 -XX:UseSSE=2` (still passes)
 - [x] Linux x86_32 fastdebug `c2/irTests` default (still passes)
 - [x] Linux x86_64 fastdebug `c2/irTests` with `-XX:UseAVX=0 -XX:UseSSE=0` (still passes)
 - [x] Linux x86_64 fastdebug `c2/irTests` with `-XX:UseAVX=0 -XX:UseSSE=1` (still passes)
 - [x] Linux x86_64 fastdebug `c2/irTests` with `-XX:UseAVX=0 -XX:UseSSE=2` (still passes)
 - [x] Linux x86_64 fastdebug `c2/irTests` default (still passes)

-------------

Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/9646/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9646&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291048
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9646.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9646/head:pull/9646

PR: https://git.openjdk.org/jdk/pull/9646