refactor map macro for more general use (#3850)

* refactor map macro for more general use

Signed-off-by: yjhmelody <465402634@qq.com>

* use $(,)?

Signed-off-by: yjhmelody <465402634@qq.com>

* Update core/primitives/src/lib.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* Update core/primitives/src/lib.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

substrate/core/primitives/src/lib.rs

@@ -26,9 +26,9 @@
 /// Can be used to create a `HashMap`.
 #[macro_export]
 macro_rules! map {
-	($( $name:expr => $value:expr ),*) => (
+	($( $name:expr => $value:expr ),* $(,)? ) => (
 		vec![ $( ( $name, $value ) ),* ].into_iter().collect()
-	)
+	);
 }
 
 use rstd::prelude::*;