This PR adds the following features:
* saturation and float rounding mode decorations,
* arithmetic constrained floating-point intrinsics (strict_fadd,
strict_fsub, strict_fmul, strict_fdiv, strict_frem, strict_fma and
strict_fldexp),
* and SPV_INTEL_float_controls2 extension,
* using recent improvements of emit-intrinsics step, this PR also
simplifies pre- and post-legalizer steps and improves instruction
selection.
978de2d666