the canonical pkg-config is getting fat. it requires glib-2. it runs pkg-
config when building. glib-2 requires pkg-config. whee.

for our normal systems, this isn't a big deal. but we'd like to enable a
lighter alternative for embedded/alternative systems. as such, i'd like to
introduce a virtual/pkgconfig that allows for selection of simpler (but
compatible) implementations.

we've got an implementation in perl (i'm not interested in), but there is also
"pkg-config-lite" and "pkgconf". they should be compatible with the canonical
pkg-config. they aren't yet in the tree, but will be once we agree on this
topic.

any comments ?
-mike