This only fails when libical is built for e.g. qemux86-64 already, and is then built for generic86-64 in a way that install is re-run:
$ MACHINE=qemux86-64 bitbake libical
$ MACHINE=genericx86-64 bitbake -f -Cinstall libical


In this case a QA check finds tmpdir in the pc file. core2-64-poky-linux libical workdir looks like this after build fails for MACHINE=genericx86-64:

$ grep iculib= build/libical.pc 
iculib=/home/jku/src/poky/build/tmp/sysroots/qemux86-64/usr/lib/libicuuc.so /home/jku/src/poky/build/tmp/sysroots/qemux86-64/usr/lib/libicui18n.so 


This is the hack in libical recipe:

do_install_append () {
        sed -i -e "s#${STAGING_LIBDIR}/lib\([a-z0-9]*\)\.so#-l\1#g" ${D}${libdir}/pkgconfig/libical.pc
}