Merge branch '5.4' into 6.4

* 5.4:
  [Validator] Check `Locale` class existence before using it

Author: derrabus

src/Symfony/Component/Validator/Test/ConstraintValidatorTestCase.php

@@ -83,8 +83,10 @@ protected function setUp(): void
         $this->validator = $this->createValidator();
         $this->validator->initialize($this->context);
 
-        $this->defaultLocale = \Locale::getDefault();
-        \Locale::setDefault('en');
+        if (class_exists(\Locale::class)) {
+            $this->defaultLocale = \Locale::getDefault();
+            \Locale::setDefault('en');
+        }
 
         $this->expectedViolations = [];
         $this->call = 0;
@@ -96,7 +98,9 @@ protected function tearDown(): void
     {
         $this->restoreDefaultTimezone();
 
-        \Locale::setDefault($this->defaultLocale);
+        if (class_exists(\Locale::class)) {
+            \Locale::setDefault($this->defaultLocale);
+        }
     }
 
     protected function setDefaultTimezone(?string $defaultTimezone)