darwin version for IOS not work anymore

[workman]

This used to work,  try with 1.27.0-beta3 get  static assert:  
`false` is false

`ldmd2 -mtriple=arm64-apple-ios14.4 -betterC test.d`

test.d
```d
version(darwin) {
	
} else {
	static assert(false);
}
```