affile: fixed flush_lines/fsync option passing

Due to a refactoring issue, the argument ordering of flush_lines()
and fsync() options were mismatched with the function implementation.

The defaults remained the same, however setting flush_lines() enabled
fsync() and setting fsync set flush_lines() to 1.

This bug was introduced in 3.4.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
configure.ac: Better hiredis detection

Instead of relying on pkg-config to detect hiredis (which is specific to
Debian and derived distributions), search for hiredis/hiredis.h on the
default include path too.

Also corrected the --with-libhiredis= case too, as it was checking for
<hiredis.h> alone, instead of <hiredis/hiredis.h>.

Signed-off-by: Gergely Nagy <algernon@balabit.hu>