WIP: [scout] Populate ABI expectations for libraries that list public symbols
For the subset of libraries where we know which symbols and/or symbol-versions are public and which are private, we can verify that we have all the ABI we need by filtering dpkg-gensymbols output according to the public symbol/symver patterns.
I've only done this for a few libraries for now:
- libgcc, because it's really important
- glibc, because it's really important
- libcurl, because it has been a practical problem in the past
- libdbus, because we use it a lot and it's easy
- GLib, because we use it a lot and it's easy
- SDL, because we use it a lot and it's easy
- some xcb libraries, because they have been a practical problem in the past