[ci skip] Fix 'sqlsrv' connect failure endless loop

Reported via the forums: http://forum.codeigniter.com/thread-61494.html
diff --git a/system/database/drivers/sqlsrv/sqlsrv_driver.php b/system/database/drivers/sqlsrv/sqlsrv_driver.php
index 16f77fa..8d383b2 100644
--- a/system/database/drivers/sqlsrv/sqlsrv_driver.php
+++ b/system/database/drivers/sqlsrv/sqlsrv_driver.php
@@ -141,13 +141,14 @@
 			unset($connection['UID'], $connection['PWD']);
 		}
 
-		$this->conn_id = sqlsrv_connect($this->hostname, $connection);
-
-		// Determine how identifiers are escaped
-		$query = $this->query('SELECT CASE WHEN (@@OPTIONS | 256) = @@OPTIONS THEN 1 ELSE 0 END AS qi');
-		$query = $query->row_array();
-		$this->_quoted_identifier = empty($query) ? FALSE : (bool) $query['qi'];
-		$this->_escape_char = ($this->_quoted_identifier) ? '"' : array('[', ']');
+		if (FALSE !== ($this->conn_id = sqlsrv_connect($this->hostname, $connection)))
+		{
+			// Determine how identifiers are escaped
+			$query = $this->query('SELECT CASE WHEN (@@OPTIONS | 256) = @@OPTIONS THEN 1 ELSE 0 END AS qi');
+			$query = $query->row_array();
+			$this->_quoted_identifier = empty($query) ? FALSE : (bool) $query['qi'];
+			$this->_escape_char = ($this->_quoted_identifier) ? '"' : array('[', ']');
+		}
 
 		return $this->conn_id;
 	}