ir_to_mesa: Stop converting uniform booleans.

ir_to_mesa: Stop converting uniform booleans.

Excess conversions considered harmful.

Recently Matt reworked the boolean uniform handling to use the value of
UniformBooleanTrue, rather than integer 1, when uploading uniforms:

    mesa: Upload boolean uniforms using UniformBooleanTrue.
    glsl: Use UniformBooleanTrue value for uniform initializers.

Marek then set the default to 1.0f for drivers without native integer
support:

    mesa: set UniformBooleanTrue = 1.0f by default

However, ir_to_mesa was assuming a value of integer 1, and arranging for
it to be converted to 1.0f on upload.  Since Marek's commit, we were
uploading 1.0f = 0x3f800000 which was being interpreted as the integer
value 1065353216 and converted to float as 1.06535322E9, which broke
assumptions in ir_to_mesa that "true" was exactly 1.0f.

+13 Piglits on classic swrast (fs-bool-less-compare-true,
{vs,fs}-op-not-bool-using-if, glsl-1.20/execution/uniform-initializer).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83573
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>