lintian: what means pkg-config-multi-arch-wrong-dir?

[debian-devel@liska.ath.cx (Olе Streicher)]

Hi,

for one of my packages (funtools) I just got a new lintian error:
pkg-config-multi-arch-wrong-dir. However, I cannot see a reason why this
is issued. The pkgconfig file (/usr/lib/pkgconfig/funtools.pc) is

--------------------8<--------------------------------
prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${prefix}/include

Name: funtools
Description: minimal buy-in FITS tools
Version: 1.4.4
Libs: -L${libdir} -lfuntools  -lz -lwcstools -ldl -lm
Cflags: -I${includedir}
--------------------8<--------------------------------

and the whole package does still not contain any connection to
mulitarch.

The lintian explanation is not really helpful here.
<http://lintian.debian.org/tags/pkg-config-multi-arch-wrong-dir.html> 

What is wrong with the pkgconfig file, or is this a bug in lintian?

Best regards

Ole