Whenever texture projection is used with a constant texture
coordinate, folding allows to use the full precision reciprocal
and not generate the lower precision reciprocal operation.

Change-Id: I6cab6567d63ecd9abe1cedbd7e46e1fd9099a3d3
Reviewed-on: https://swiftshader-review.googlesource.com/5210Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>