This directory holds sources for modules not built through PIP.
Their sub-directories should be named "lib-${LIB_VERSION}", to be picked up
through the EXTRA_LIBRARIES variable in the "chevah_build" shell script.

Patches for these modules should reside in a sub-directory named
"lib-${LIB_VERSION}-patches", to be applied when needed during the build.
See the patches for `scandir` for an example involving multiple patches
to be applied in a predetermined order.

For some modules built through PIP we keep source here as well because
some of the files are needed in the test phase ('scandir' for now).