glsl/softfp64: GC the temp vars after we lower them to SSA.

They don't serve any purpose other than taking up memory and cluttering
your compiler output at this point.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22083>

src/compiler/glsl/glsl_to_nir.cpp

@@ -2852,6 +2852,7 @@ glsl_float64_funcs_to_nir(struct gl_context *ctx,
     * with compile times.
     */
    NIR_PASS_V(nir, nir_lower_vars_to_ssa);
+   NIR_PASS_V(nir, nir_remove_dead_variables, nir_var_function_temp, NULL);
    NIR_PASS_V(nir, nir_copy_prop);
    NIR_PASS_V(nir, nir_opt_dce);
    NIR_PASS_V(nir, nir_opt_cse);