[libc++] Alphabetize header inclusions and include-what-you-use <__debug>. NFCI.

NOKEYCHECK=True
GitOrigin-RevId: 06b40e80aefc9a7ccf2efbf7717037bd103a779c
diff --git a/include/regex b/include/regex
index 6104ce3..dafb0e6 100644
--- a/include/regex
+++ b/include/regex
@@ -763,16 +763,17 @@
 */
 
 #include <__config>
-#include <stdexcept>
+#include <__debug>
 #include <__locale>
 #include <compare>
-#include <initializer_list>
-#include <utility>
-#include <iterator>
-#include <string>
-#include <memory>
-#include <vector>
 #include <deque>
+#include <initializer_list>
+#include <iterator>
+#include <memory>
+#include <stdexcept>
+#include <string>
+#include <utility>
+#include <vector>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)