Fix location of assignable nodes

* parse.y (node_assign_gen): In some case assignable nodes
  are created before rhs is created. In this case it is
  needed to set location after rhs is shifted to
  rhs range be included to assignable nodes.

  e.g. The locations of NODE_DASGN_CURR is fixed:

  ```
  a = 10
  ```

  * Before

  ```
  NODE_DASGN_CURR (line: 1, first_lineno: 1, first_column: 0, last_lineno: 1, last_column: 1)
  ```

  * After

  ```
  NODE_DASGN_CURR (line: 1, first_lineno: 1, first_column: 0, last_lineno: 1, last_column: 6)
  ```

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60816 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

parse.y

@@ -10119,6 +10119,7 @@ node_assign_gen(struct parser_params *parser, NODE *lhs, NODE *rhs, const YYLTYP
       case NODE_CDECL:
       case NODE_CVASGN:
 	lhs->nd_value = rhs;
+	lhs->nd_loc = *location;
 	break;
 
       case NODE_ATTRASGN: