Update rust-profiler sanity test

Desugar the for-loop to minimize ambiguity when testing the profiler.

The original regression is tracked upstream as rust#151554.

For: RUST-52

tests/Sanity/rust-profiler/coverage.exp

@@ -1,10 +1,11 @@
-    1|      1|fn main(){
+    1|      1|fn main() {
     2|      1|    let mut sum: u32 = 0;
-    3|     10|    for i in 1..10 {
-    4|      9|        sum += i;
-    5|      9|    }
-    6|      1|    if false{
-    7|      0|        println!("This code can't be reached");
-    8|      1|    }
-    9|      1|    println!("Sum: {}", sum);
-   10|      1|}
+    3|      1|    let mut iter = 1..10;
+    4|     10|    while let Some(i) = iter.next() {
+    5|      9|        sum += i;
+    6|      9|    }
+    7|      1|    if false {
+    8|      0|        println!("This code can't be reached");
+    9|      1|    }
+   10|      1|    println!("Sum: {}", sum);
+   11|      1|}

tests/Sanity/rust-profiler/main.rs

@@ -1,9 +1,10 @@
-fn main(){
+fn main() {
     let mut sum: u32 = 0;
-    for i in 1..10 {
+    let mut iter = 1..10;
+    while let Some(i) = iter.next() {
         sum += i;
     }
-    if false{
+    if false {
         println!("This code can't be reached");
     }
     println!("Sum: {}", sum);