Emit SSE2 compatible operations if SSE4.1 is not supported.
Emit SSE2 compatible operations if SSE4.1 is not supported.

Bug swiftshader:20

Change-Id: I67818bfe10cb29211559fb2ee047f6bec6ce46d4
Reviewed-on: https://swiftshader-review.googlesource.com/8451
Tested-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>
Reviewed-by: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>
Reviewed-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>

google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader