Move JVM-specific annotations out of built-ins

Move 'volatile' and 'synchronized' to package 'kotlin' in stdlib. Also delete
'atomic', since its support was never implemented

core/builtins/native/jet/Library.kt

@@ -2,10 +2,6 @@ package jet
 
 public trait Annotation
 
-public annotation class volatile
-
-public fun <R> synchronized(lock: Any, block: () -> R): R
-
 public fun Any?.identityEquals(other: Any?): Boolean // = this === other
 
 public fun Any?.equals(other: Any?): Boolean