Fix comment in ExprKind::LogicalOp

The comment previously implied that the true branch would result in the false
block. Fortunately the implementation is correct.

src/librustc_mir/build/expr/into.rs

@@ -104,8 +104,8 @@ pub fn into_expr(&mut self,
                 // Or:
                 //
                 // [block: If(lhs)] -false-> [else_block: If(rhs)] -true-> [true_block]
-                //        |                          | (false)
-                //        +----------true------------+-------------------> [false_block]
+                //        | (true)                   | (false)
+                //  [true_block]               [false_block]
 
                 let (true_block, false_block, mut else_block, join_block) =
                     (this.cfg.start_new_block(), this.cfg.start_new_block(),