[ADT] Don't include <algorithm> in iterator.h

As far as I can tell, nothing in iterator.h uses anything from <algorithm>.

Differential Revision: https://reviews.llvm.org/D100659

GitOrigin-RevId: da627258742ae638b813d0341f069d5b4a6bd9ae
diff --git a/include/llvm/ADT/iterator.h b/include/llvm/ADT/iterator.h
index 5b304df..7f54290 100644
--- a/include/llvm/ADT/iterator.h
+++ b/include/llvm/ADT/iterator.h
@@ -10,7 +10,6 @@
 #define LLVM_ADT_ITERATOR_H
 
 #include "llvm/ADT/iterator_range.h"
-#include <algorithm>
 #include <cstddef>
 #include <iterator>
 #include <type_traits>