php multiversion sets PKG_SYSCONFSUBDIR (I think wrongly)

[Greg Troxel <gdt%lexort.com@localhost>]

I found that zoneminder was broken, and tracked it down to in
lang/php/phpversion.mk:

  PKG_SYSCONFSUBDIR?=     php/${PHP_API_VERS}

I think this is incorrect, as a package shouldn't get its sysconfdir
changed just because it's using php.

I avoided zoneminder being configured for the wrong conf directory by
setting PKG_SYSCONFSUBDIR in the zoneminder Makefile before including
php, but I think this line should be removed -- and I don't know where
it needs to go instead.

While it feels like a big change at end of freeze, I think it is likely
to break other packages at runtime, even if they build ok, so I believe
we should fix it now.