Update some doc examples to accommodate new by-value upvar closures.

Author: pnkfelix

src/doc/guide-container.md

@@ -184,8 +184,9 @@ let xs = [1,2,3,4,5];
 let mut calls = 0;
 
 {
+    let calls_ref = &mut calls;
     let it = xs.iter().scan((), |_, x| {
-        calls += 1;
+        *calls_ref += 1;
         if *x < 3 { Some(x) } else { None }});
 
     // the iterator will only yield 1 and 2 before returning None

src/doc/tutorial.md

@@ -1838,7 +1838,8 @@ access local variables in the enclosing scope.
 
 ~~~~
 let mut max = 0;
-let f = |x: int| if x > max { max = x };
+let max_ref = &mut max;
+let f = |x: int| if x > *max_ref { *max_ref = x };
 for x in [1, 2, 3].iter() {
     f(*x);
 }