The bin-* and lib-* files are used for building phony guest images
(see test-data/phony-guests).

The bin-* files are generated from empty source files (ie.
"main(){}") on the respective architectures.

The lib-* files are generated from a (really) empty source file called
lib.c which is linked into a library using gcc -shared on the
respective architectures.

If you are concerned that these binary files "lack source" then you
can just remove them, but you may need to patch out various tests.
