Opcodes for soon to be added integer operations such as:
- Conversions to/from float
- Negate
- Comparison
- Add, Sub, Mul, Div, Mod
- Left Shift, Right Shift
- Min, Max

Change-Id: I16af0423fdb210a558ad293e0e043176bde1c9ee
Reviewed-on: https://swiftshader-review.googlesource.com/3889Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>