Upgrade/Install: Update sodium_compat to v1.21.2.

Version 1.21.2 is mostly to prevent deprecation warnings on PHP 8.5. These should never be encountered in practice (as the only file in scope was an `SplFixedArray` polyfill for PHP 5.2, which should never be executed on PHP 8.5), but for completeness the polyfill was updated.

References:
* [https://github.com/paragonie/sodium_compat/releases/tag/v1.21.2 sodium_compat 1.21.2 release notes]
* [paragonie/sodium_compat@v1.20.1...v1.21.2 Full list of changes in sodium_compat 1.21.2]

Follow-up to [55699], [58752], [58753].

Props paragoninitiativeenterprises, jrf, johnbillion, TobiasBg, SergeyBiryukov.
Fixes #64008.

git-svn-id: https://develop.svn.wordpress.org/trunk@60787 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/sodium_compat/src/PHP52/SplFixedArray.php

@@ -32,6 +32,7 @@ public function __construct($size = 0)
     /**
      * @return int
      */
+    #[\ReturnTypeWillChange]
     public function count()
     {
         return count($this->internalArray);
@@ -72,6 +73,7 @@ public static function fromArray(array $array, $save_indexes = true)
     /**
      * @return int
      */
+    #[\ReturnTypeWillChange]
     public function getSize()
     {
         return $this->size;
@@ -81,6 +83,7 @@ public function getSize()
      * @param int $size
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function setSize($size)
     {
         $this->size = $size;
@@ -91,6 +94,7 @@ public function setSize($size)
      * @param string|int $index
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($index)
     {
         return array_key_exists((int) $index, $this->internalArray);
@@ -100,6 +104,7 @@ public function offsetExists($index)
      * @param string|int $index
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($index)
     {
         /** @psalm-suppress MixedReturnStatement */
@@ -111,6 +116,7 @@ public function offsetGet($index)
      * @param mixed $newval
      * @psalm-suppress MixedAssignment
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($index, $newval)
     {
         $this->internalArray[(int) $index] = $newval;
@@ -119,6 +125,7 @@ public function offsetSet($index, $newval)
     /**
      * @param string|int $index
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($index)
     {
         unset($this->internalArray[(int) $index]);
@@ -130,6 +137,7 @@ public function offsetUnset($index)
      * @return void
      * @since 5.3.0
      */
+    #[\ReturnTypeWillChange]
     public function rewind()
     {
         reset($this->internalArray);
@@ -141,6 +149,7 @@ public function rewind()
      * @return mixed The current element value.
      * @since 5.3.0
      */
+    #[\ReturnTypeWillChange]
     public function current()
     {
         /** @psalm-suppress MixedReturnStatement */
@@ -151,6 +160,7 @@ public function current()
      * Return current array index
      * @return int The current array index.
      */
+    #[\ReturnTypeWillChange]
     public function key()
     {
         return key($this->internalArray);
@@ -159,6 +169,7 @@ public function key()
     /**
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function next()
     {
         next($this->internalArray);
@@ -169,6 +180,7 @@ public function next()
      * @link https://php.net/manual/en/splfixedarray.valid.php
      * @return bool true if the array contains any more elements, false otherwise.
      */
+    #[\ReturnTypeWillChange]
     public function valid()
     {
         if (empty($this->internalArray)) {
@@ -179,11 +191,31 @@ public function valid()
         return $result;
     }
 
+    public function __sleep()
+    {
+        return $this->internalArray;
+    }
+
     /**
      * Do nothing.
      */
     public function __wakeup()
     {
         // NOP
     }
-}
+
+    public function __serialize()
+    {
+        return array_values($this->internalArray);
+    }
+
+    public function __unserialize(array $data)
+    {
+        $length = count($data);
+        $values = array_values($data);
+        for ($i = 0; $i < $length; ++$i) {
+            $this->internalArray[$i] = $values[$i];
+        }
+        $this->size = $length;
+    }
+}