./configure should use pkg-config
When flac, speex and/or ogg are installed in non-standard locations, configure does not find them, even though pkg-config knows about the locations.
For ogg, this is a minor nuisance (adding --with-ogg=$LIBOGG_ROOT works), but for flac and speex there are no such configure parameters and one has to resort to more ugly clutches:
CFLAGS=pkg-config --cflags flac speex
LDFLAGS=pkg-config --libs flac speex
I haven't checked, but maybe the same applies to libkate.
This bug is related to bug #1780.