Fix locations of NODE_LAMBDA.

* node.h: Add `nd_first_loc` and `nd_set_first_loc`

* parse.y: Fix to start with the beginning of `->` .

  e.g. The locations of the NODE_LAMBDA is fixed:

  ```
  -> x { 1 + 2 }
  ```

  * Before

  ```
  NODE_LAMBDA (line: 1, location: (1,2)-(1,14))
  ```

  * After

  ```
  NODE_LAMBDA (line: 1, location: (1,0)-(1,14))
  ```

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65221 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

node.h

@@ -192,6 +192,8 @@ typedef struct RNode {
 #define nd_set_first_column(n, v) ((n)->nd_loc.beg_pos.column = (v))
 #define nd_first_lineno(n) ((int)((n)->nd_loc.beg_pos.lineno))
 #define nd_set_first_lineno(n, v) ((n)->nd_loc.beg_pos.lineno = (v))
+#define nd_first_loc(n) ((n)->nd_loc.beg_pos)
+#define nd_set_first_loc(n, v) (nd_first_loc(n) = (v))
 
 #define nd_last_column(n) ((int)((n)->nd_loc.end_pos.column))
 #define nd_set_last_column(n, v) ((n)->nd_loc.end_pos.column = (v))

parse.y

@@ -2443,6 +2443,9 @@ primary		: literal
 		  lambda
 		    {
 			$$ = $3;
+                    /*%%%*/
+                        nd_set_first_loc($$, @1.beg_pos);
+                    /*% %*/
 		    }
 		| k_if expr_value then
 		  compstmt