Attempt to mitigate travis ci's mysterious "cannot find symbol: class Retention" errors

Author: ochafik

Core/src/main/velocity/com/nativelibs4java/opencl/CLException.java

@@ -32,11 +32,6 @@ public int getCode() {
         return code;
     }
 
-	@Retention(RetentionPolicy.RUNTIME)
-	public @interface ErrorCode {
-		int value();
-	}
-
 	public static class CLVersionException extends CLException {
 		public CLVersionException(String message) {
 			super(message, 0);
@@ -272,3 +267,8 @@ public static void error(int err) {
         throw toThrow;
     }
 }
+
+@Retention(RetentionPolicy.RUNTIME)
+@interface ErrorCode {
+  int value();
+}