fix MySQL build problems with ConnectionException detection

lib/Doctrine/DBAL/Driver/AbstractMySQLDriver.php

@@ -90,7 +90,14 @@ public function convertException($message, DriverException $exception)
  case '1429':
  case '2002':
  case '2005':
+ case '2054':
  return new Exception\ConnectionException($message, $exception);
+
+ case '2006':
+ if ($exception instanceof Driver\Mysqli\MysqliConnectionException || $exception instanceof PDOConnectionException) {
+ return new Exception\ConnectionException($message, $exception);
+ }
+ break;
 
  case '1048':
  case '1121':

lib/Doctrine/DBAL/Driver/Mysqli/MysqliConnectionException.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace Doctrine\DBAL\Driver\Mysqli;
+
+/**
+ * Exception thrown in case the mysqli driver errors while connecting.
+ */
+class MysqliConnectionException extends MysqliException
+{
+}

lib/Doctrine/DBAL/Driver/PDOConnection.php

@@ -28,7 +28,7 @@ public function __construct($dsn, $user = null, $password = null, ?array $option
  $this->setAttribute(PDO::ATTR_STATEMENT_CLASS, [PDOStatement::class, []]);
  $this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
  } catch (\PDOException $exception) {
- throw new PDOException($exception);
+ throw new PDOConnectionException($exception);
  }
  }
 

lib/Doctrine/DBAL/Driver/PDOConnectionException.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace Doctrine\DBAL\Driver;
+
+/**
+ * PDOConnectionException is used to distinguish connection failures from regular PDOExceptions.
+ */
+class PDOConnectionException extends PDOException
+{
+}