Merge bitcoin#23181: refactor: remove references to deprecated values under std::allocator

ea4b61a refactor: remove references to deprecated values under std::allocator (Pasta)

Pull request description:

  Removes usages of allocator::pointer, allocator::const_pointer, allocator::reference and allocator::const_reference which are deprecated in c++17 and **removed** in c++20. See https://en.cppreference.com/w/cpp/memory/allocator

  Also prefers `using` over `typedef` see: https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rt-using I'll be happy to revert this if requested so

ACKs for top commit:
  laanwj:
    Re-ACK ea4b61a

Tree-SHA512: 9353e47a7de27bcd91b341eb2d832318b51fce9f508fcc791f05c02c5a160f430f4e7214e76f4b3e29639750d311c679789d8b7409255b13637391e4575c9ebe

Author: laanwj

src/support/allocators/secure.h

@@ -9,6 +9,7 @@
 #include <support/lockedpool.h>
 #include <support/cleanse.h>
 
+#include <memory>
 #include <string>
 
 //
@@ -17,15 +18,13 @@
 //
 template <typename T>
 struct secure_allocator : public std::allocator<T> {
-    // MSVC8 default copy constructor is broken
-    typedef std::allocator<T> base;
-    typedef typename base::size_type size_type;
-    typedef typename base::difference_type difference_type;
-    typedef typename base::pointer pointer;
-    typedef typename base::const_pointer const_pointer;
-    typedef typename base::reference reference;
-    typedef typename base::const_reference const_reference;
-    typedef typename base::value_type value_type;
+    using base = std::allocator<T>;
+    using traits = std::allocator_traits<base>;
+    using size_type = typename traits::size_type;
+    using difference_type = typename traits::difference_type;
+    using pointer = typename traits::pointer;
+    using const_pointer = typename traits::const_pointer;
+    using value_type = typename traits::value_type;
     secure_allocator() noexcept {}
     secure_allocator(const secure_allocator& a) noexcept : base(a) {}
     template <typename U>

src/support/allocators/zeroafterfree.h

@@ -13,15 +13,13 @@
 
 template <typename T>
 struct zero_after_free_allocator : public std::allocator<T> {
-    // MSVC8 default copy constructor is broken
-    typedef std::allocator<T> base;
-    typedef typename base::size_type size_type;
-    typedef typename base::difference_type difference_type;
-    typedef typename base::pointer pointer;
-    typedef typename base::const_pointer const_pointer;
-    typedef typename base::reference reference;
-    typedef typename base::const_reference const_reference;
-    typedef typename base::value_type value_type;
+    using base = std::allocator<T>;
+    using traits = std::allocator_traits<base>;
+    using size_type = typename traits::size_type;
+    using difference_type = typename traits::difference_type;
+    using pointer = typename traits::pointer;
+    using const_pointer = typename traits::const_pointer;
+    using value_type = typename traits::value_type;
     zero_after_free_allocator() noexcept {}
     zero_after_free_allocator(const zero_after_free_allocator& a) noexcept : base(a) {}
     template <typename U>