New integer related core functions

New integer related core functions

- Removed float <-> int bit conversion functions, as these
  will not be needed if everything is stored as float.
- Added ineg for the minus (-) sign in from of a value.
- Added f2i/i2f/f2u/u2f for float <-> int conversions
- Added b2i/i2b/b2u/u2b for bool <-> int conversions
- Added iadd, isub, imul, imad, [iu]div, [iu]mod, [iu]min,
  [iu]max for these basic operations as integer operations.
- Added left and right shifts
- Added ucmp to compare unsigned values
- Modified or/xor/and to support vectors instead of only
  scalars.
- Added vector equality comparison functions

Change-Id: I0f138e3707242ec0fffc1c12b95064ddc98f0087
Reviewed-on: https://swiftshader-review.googlesource.com/3888
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>