machinst x64: implement float Floor/Ceil/Trunc/Nearest as VM calls;

cranelift/codegen/meta/src/shared/settings.rs

@@ -270,7 +270,7 @@ pub(crate) fn define() -> SettingGroup {
         "enable_heap_access_spectre_mitigation",
         r#"
         Enable Spectre mitigation on heap bounds checks.
-        
+
         This is a no-op for any heap that needs no bounds checks; e.g.,
         if the limit is static and the guard region is large enough that
         the index cannot reach past it.