Don't allow some E_NOTICE messages to end up in the LocalSettings.php

There is probably a better, more comprehensive way to produce a
LocalSettings.php file so that E_STRICT and E_NOTICE errors don't end
up in the file, or to notify users that there is a problem with the
generated file, at least.   This only attempts to address those issues
reported as a result of c978cee8562f018dab158b41e15266fcf873bf1b.

Bug: 66922
Change-Id: I0fe70446d9fe23aed2a147e20e5ff3851371726d