Now, resolve-lib can take a big list of libraries with full paths,
and it can solve a big list of spec at once.
Basically, we move most of the parsing of spec paths into resolve-lib.
Since print-package-signature does build a full list of libs, let's solve
it all at once, instead of invoking a costly perl script repeatedly.
Add some caching possibilities for out-of-date. Specifically:
- store libraries for each package under the directory _PORT_LIBS_CACHE
- use the dependency cache _DEPENDS_FILE to avoid recreating dependency
chains, add a new file _DEPENDS_CACHE that will accumulate all dependencies,
and extract these with a simple script extract-dependencies.
Use echo to build libraries lists instead of ls, that's a bit simpler...
Some more clean-up will happen: it's probably simpler to parse libspecs
at once, extract the libraries needed and go fetch the corresponding libraries
just once.
