Disable new sroa now that all buildbots have tested it.

What we have so far:
- Some clang test failures (these were known already)

- Perf results are mixed, some big regressions
  http://llvm.org/perf/db_default/v4/nts/3844
  http://llvm.org/perf/db_default/v4/nts/3845

  bullet suffers a lot. matmul is interesting: slower scalar code, faster with -vectorize.

- Some dragonegg selfhost bots crash in SROA during selfhost now
  http://lab.llvm.org:8011/builders/dragonegg-x86_64-linux-gcc-4.6-self-host-checks/builds/1632
  http://lab.llvm.org:8011/builders/dragonegg-x86_64-linux-gcc-4.5-self-host/builds/1891

llvm-svn: 163968