Decrease the size of UA_DataValue

Shrink the size from 96 bytes to 80 bytes by reordering members to avoid padding
(64bit linux).

include/ua_types.h

@@ -716,18 +716,18 @@ typedef struct {
  * ^^^^^^^^^
  * A data value with an associated status code and timestamps. */
 typedef struct {
+    UA_Variant    value;
+    UA_DateTime   sourceTimestamp;
+    UA_DateTime   serverTimestamp;
+    UA_UInt16     sourcePicoseconds;
+    UA_UInt16     serverPicoseconds;
+    UA_StatusCode status;
     UA_Boolean    hasValue             : 1;
     UA_Boolean    hasStatus            : 1;
     UA_Boolean    hasSourceTimestamp   : 1;
     UA_Boolean    hasServerTimestamp   : 1;
     UA_Boolean    hasSourcePicoseconds : 1;
     UA_Boolean    hasServerPicoseconds : 1;
-    UA_Variant    value;
-    UA_StatusCode status;
-    UA_DateTime   sourceTimestamp;
-    UA_UInt16     sourcePicoseconds;
-    UA_DateTime   serverTimestamp;
-    UA_UInt16     serverPicoseconds;
 } UA_DataValue;
 
 /**