Strict autotools API checks

[ryao]

Currently, many configure script checks for API changes make assumptions that if one interface is not used, the other must be used. Unfortunately, that assumption causes problems should the interface change again. Building --with-debug will address that through a compile time failure, but few end users do, which can result in difficult to debug runtime failures that are rather frustrating for users (e.g. issue #843). We can address that by changing the existing checks to check all known cases and forcing a failure if no known case is detected. Once that is done, all future configure script checks should be required to follow the same standard.

This is also related to issue #582, which could probably be tackled at the same time.

[ryao]

Issue #1004 would have been easier to diagnose if this was in place. It also seems that it would be wise to run all checks even if a failure is detected occurs so that we can obtain a list of issues more easily.

[behlendorf]

This is still a good idea, time permitting.

[behlendorf]

This remains a good idea if someone wants to work on it, but the existing system has been working well for several years now.