Remove `disabled` attribute from `unimplemented`

core/runtime/core_builtin.odin

@@ -826,7 +826,6 @@ panic :: proc(message: string, loc := #caller_location) -> ! {
 }
 
 @builtin
-@(disabled=ODIN_DISABLE_ASSERT)
 unimplemented :: proc(message := "", loc := #caller_location) -> ! {
 	p := context.assertion_failure_proc
 	if p == nil {