There are lots of files that don't need it: The number of object
files that actually need it went down from 2011 to 884 here.
Keep it for external users in order to not cause breakages.
Also improve the other headers a bit while just at it.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
internal.h doesn't rely on it; instead include it directly
in every user that needs it (a filter needing it is basically
equivalent to it using FILTER_QUERY_FUNC, i.e. a majority of
filters doesn't need it).
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
