This commit fills in the unimplemented non-x86 (generic) code generator.

Change-Id: I189b0ea523ecd9b18c29ad6ed6fa3f798382295b
Reviewed-on: https://swiftshader-review.googlesource.com/20476Tested-by: Logan Chien <loganchien@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>