Since we switched from autotools to Meson in commit
94592c1406, we don't need to include
`config.h` early to properly enable large file support. Meson passes
the required macros on the compiler command line instead of defining
them in `config.h`.
This means we can include `config.h` at any time, whenever we want to
check its macros, and there are no ordering constraints.
The protocol documentation says that the difference between `find` and
`search` is that `search` is case insensitive, but that's only half
the truth: `search` also searches for sub strings instead of matching
the whole string. This part is undocumented and unfortunate, but at
this point, we can't change it.
However leaking this surprising behavior to the new filter expressions
was a bad idea; the "==" operator should never match substrings. For
people who need that, we should add a new operator.
