Fixed the regression in .../sungeun/iteration/forall.chpl from #324
Merge pull request #355 from vasslitvinov/fix-tuple/sungeun/iteration/forall.chpl-regression

Fixed the regression in .../sungeun/iteration/forall.chpl from #324

The changes are:

* Removed an assignment to 'e' in

    forall e in t1 do e = sum.fetchAdd(1);

* Removed the check:

    forall e in t1 do if e!=0.0 then halt("Element should be zero!");

According to Sung, the assignment e=... was not intended
to actually modify t1's elements. Indeed, the now-removed
check was verifying that the modification did not happen.

Now that the assignment e=... is officially illegal,
we removed it and the now-moot check as well.