swift234

[sema] Add a fixit for label-mismatch tuple patterns in for-each statement. rdar://25671800

In the following code example, compiler emits an error of "cannot express tuple conversion...". However,
this is trivially fixable by adding multiple labels in the tuple pattern of the for-each statement. This
commit adds such fixit.

func foo(array : [(some: Int, (key: Int, value: String))]) {
  for (i, (k, v)) in array {
  }
}