Add newline character to end of mt19937.c

The change ensures that the file conforms to the standard of having a
newline character at the end.

Author: visitorckw

tests/map/mt19937.c

@@ -43,4 +43,4 @@ uint64_t mt19937_extract()
 
     index = (index + 1) % 624;
     return y;
-}
+}