Overlays: The dependencies right now are approximate, and when new overlays are

added the build breaks. There's already a tool to get proper
dependencies, `utils/find-overlay-dependencies.sh`, so this patch
allows that tool to update the `CMakeLists.txt` files in-place.

Also it adds a line to the `CMakeLists.txt` files for each SDK so that the tool works.

utils/find-overlay-dependencies-loop.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+#===--- find-overlay-dependencies-loop.sh - driver for find-overlay-dependency.sh---===#
+#
+## This source file is part of the Swift.org open source project
+##
+## Copyright (c) 2016 Apple Inc. and the Swift project authors
+## Licensed under Apache License v2.0 with Runtime Library Exception
+##
+## See http://swift.org/LICENSE.txt for license information
+## See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+#
+#===------------------------------------------------------------------------===#
+
+SCRIPT="$(dirname "$0")/find-overlay-dependencies.sh"
+
+# `update` edits the cmake file in-place; `print` just prints to console
+function usage() {
+  echo 'usage:' $0 'update|print' >&2
+    exit 1
+}
+
+case $# in
+1) if [[ $1 != 'update' && $1 != 'print' ]]; then
+    usage
+  fi ;;
+*)
+  usage ;;
+esac
+
+# Don't update XCTest
+for overlay in $(find ./stdlib/public/SDK/ -depth 1 -type d ! -name XCTest -exec basename \{\} \;); do
+  $SCRIPT $overlay $1
+done