serialization / APC / igbinary. about apcu

[remicollet]

For your information : igbinary/igbinary#24
This fix seems simpler / better than the one propose in #21

[weltling]

Looking at here https://github.com/igbinary/igbinary/blob/master/config.m4 it wants apc/apc_serializer.h . Clear that the folder can be renamed from apcu to apc, but i'd say that's not the right way to do. Doesn't it look so that one should touch igbinary ext for compat? Maybe explicit options like --with-apc-path or --with-apcu-path which should be mutually exclusive. Just wanted to test together with igbinary but not sure how to do it right.

[remicollet]

See #25

With this change (restore previous ABI) igbinary will work out of the box (using the bundled apc_serializer.h or apc one, or apcu one).

Of course a minor change to check ext/apcu folder is a cleaner solution (for the future).
As apc/apcu can't be both installed, so checking sequentially each folder in the config.m4 file seems ok (see igbinary PR, which need to be improved if this PR is accepted)

[weltling]

Actually the both can be installed but not loaded, so the headers of both might be laying around in the include path. That's good for apcu, but not apc users :) I think some WTFs from APC+igbinary users are to expect.

[remicollet]

What would be the problem ? As far as the ABI is the same ?

[weltling]

Well, if user has both apc and apcu and compiles igbinary then hoping for apc but seeing apcu in the phpinfo(). For that reason i'd rather force user to choose one instead of doing it silently. With the same ABI it'd of course work, or at least it'll load together.