os.name property is expected to be Mac OS X on Apple computers

Signed-off-by: Ceki Gulcu <[email protected]>

logback-core/src/main/java/ch/qos/logback/core/util/EnvUtil.java

@@ -128,6 +128,7 @@ static public boolean isJaninoAvailable() {
 
     public static boolean isMacOs() {
         String os = System.getProperty("os.name");
+        // expected value is "Mac OS X"
         return os.toLowerCase().contains("mac");
     }