Improve syntax error reporting

In some cases the error information is not enough to debug it.

Before:

syntax error, unexpected '<<' (T_SL)
/var/www/html/lib/private/AppFramework/Http/Dispatcher.php
158

After:

syntax error, unexpected '<<' (T_SL) in file '/var/www/html/apps/groupfolders/lib/Mount/GroupFolderStorage.php' line 88
/var/www/html/lib/private/AppFramework/Http/Dispatcher.php
158

Signed-off-by: Carl Schwan <carl@carlschwan.eu>