If a package `foo` doesn't implement `libs`, the default was to search recursively for `libfoo` whenever asking for `spec[foo].libs` (this also happens automatically if a package includes `foo` as a link dependency).
This can lead to some strange behavior:
1. A package that is normally used as a build dependency (e.g. `cmake` at one point) is referenced like
`depends_on(cmake)` which leads to a fully-recursive search for `libcmake` (this can take
"forever" when CMake is registered as an external with a prefix like `/usr`, particularly on NFS mounts).
2. A similar hang can occur if a package is registered as an external with an incorrect prefix
- [x] Update the default library search to stop after a maximum depth (by default, search
the root prefix and each directory in it, but no lower).
- [x]
The following is a list of known changes to `find` compared to `develop`:
1. Matching directories are no longer returned -- `find` consistently only finds non-dirs,
even at `max_depth`
2. Symlinked directories are followed (needed to support max_depth)
3. `find(..., "dir/*.txt")` is allowed, for finding files inside certain dirs. These "complex"
patterns are delegated to `glob`, like they are on `develop`.
4. `root` and `files` arguments both support generic sequences, and `root`
allows both `str` and `path` types. This allows us to specify multiple entry points to `find`.
---------
Co-authored-by: Peter Scheibel <scheibel1@llnl.gov>
907a37145f