nir/algebraic: disable inexact optimizations depending on float controls execution...

nir/algebraic: disable inexact optimizations depending on float controls execution mode

If FLOAT_CONTROLS_SIGNED_ZERO_INF_NAN_PRESERVE or
FLOAT_CONTROLS_DENORM_FLUSH_TO_ZERO are enabled, do not apply the
inexact optimizations so the VK_KHR_shader_float_controls execution
mode is respected.

v2:
- Do not apply inexact optimizations if SHADER_DENORM_FLUSH_TO_ZERO is
  enabled (Andres).

v3:
- Updated to renamed shader info member (Andres).

v4:
- Directly access execution mode instead of dragging it by parameter (Caio).

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Signed-off-by: Andres Gomez <agomez@igalia.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com> [v1]