* LLVM reactor backend: requires LLVM 7.0
* Subzero reactor backend: unittests hit unimplemented
  TargetMIPS32::lowerShuffleVector()

Bug: b/117854176
Change-Id: Ie58e3e438db6f1b442b05efecf9b645aff82321a
Reviewed-on: https://swiftshader-review.googlesource.com/c/21748Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Milko Leporis <milko.leporis@mips.com>