Remove FloatFast option for glsl-optimizer

[nathanstouffer]

Summary

When I use clang version 17 to compile shaderc, the resulting essl/glsl shaders have all constants replaced with the value (-1.0/0.0). Removing FloatFast for the glsl-optimizer target resolved the issue for me.

Minimum Reproducible Example

$input a_position

void main()
{
    gl_Postition = vec4(0.0, 0.0, 0.0, 1.0);
}

precision highp int;
precision highp float;
void main()
{
    gl_Position = vec4((-1.0/0.0), (-1.0/0.0), (-1.0/0.0), (-1.0/0.0));
}

[bkaradzic]

Move the removeflags block into glsl-optimizer.