Deprecated in favor of std.lang.Optimize.runtimeSafety, to be removed after 0.18.0
Returns whether the standard library has safety checks enabled. Callsites
likely would rather know whether their own module's optimization mode
(found via @import("builtin").optimize) has safety checks enabled.
pub const runtime_safety = builtin.mode.runtimeSafety()
pub const runtime_safety = builtin.mode.runtimeSafety()