imlib2-config was dropped

[RamKromberg]

imlib2 dropped imlib2-config so idesk fails to build right now:

203 v1.7.5 - 2021-12-06
204 --------------------
205 Kim Woelders (83):
206 Build .xz instead of .bz2 release tarball
207 Drop imlib2-config (use pkg-config)
( https://fossies.org/linux/imlib2/ChangeLog )

https://github.com/neagix/idesk/blob/master/configure#L6961-L7076
https://github.com/neagix/idesk/blob/master/configure.in#L95-L110

A rough workaround:

sed -i -e '95,101d;' configure.in
sed -i 's/imlib2-config --libs/pkg-config --libs imlib2/g' configure.in
sed -i 's/imlib2-config --cflags/pkg-config --cflags imlib2/g' configure.in
sed -i -e '6961,7063d;' configure
sed -i 's/imlib2-config --libs/pkg-config --libs imlib2/g' configure
sed -i 's/imlib2-config --cflags/pkg-config --cflags imlib2/g' configure
sed -i 's/imlib2-config/pkg-config/g' configure