Use fully qualifed name for DescriptorPool in Any.php to avoid name (#3886)

conflict

php/src/Google/Protobuf/Any.php

@@ -4,7 +4,6 @@
 
 namespace Google\Protobuf;
 
-use Google\Protobuf\Internal\DescriptorPool;
 use Google\Protobuf\Internal\GPBType;
 use Google\Protobuf\Internal\GPBUtil;
 use Google\Protobuf\Internal\Message;
@@ -217,7 +216,7 @@ class Any extends \Google\Protobuf\Internal\Message
             substr($this->type_url, $url_prifix_len);
 
         // Create message according to fully qualified name.
-        $pool = DescriptorPool::getGeneratedPool();
+        $pool = \Google\Protobuf\Internal\DescriptorPool::getGeneratedPool();
         $desc = $pool->getDescriptorByProtoName( ".".$fully_qualifed_name);
         if (is_null($desc)) {
             throw new \Exception("Class ".$fully_qualifed_name
@@ -248,7 +247,7 @@ class Any extends \Google\Protobuf\Internal\Message
         $this->value = $msg->serializeToString();
 
         // Set type url.
-        $pool = DescriptorPool::getGeneratedPool();
+        $pool = \Google\Protobuf\Internal\DescriptorPool::getGeneratedPool();
         $desc = $pool->getDescriptorByClassName(get_class($msg));
         $fully_qualifed_name = $desc->getFullName();
         $this->type_url = GPBUtil::TYPE_URL_PREFIX.substr(
@@ -262,7 +261,7 @@ class Any extends \Google\Protobuf\Internal\Message
      */
     public function is($klass)
     {
-        $pool = DescriptorPool::getGeneratedPool();
+        $pool = \Google\Protobuf\Internal\DescriptorPool::getGeneratedPool();
         $desc = $pool->getDescriptorByClassName($klass);
         $fully_qualifed_name = $desc->getFullName();
         $type_url = GPBUtil::TYPE_URL_PREFIX.substr(