This is the result of running $ uncrustify --replace --config ../devel/uncrustify.cfg *.c *.h in the compat directory
We may switch to using an autoconf-like config.h, but we're not doing that just yet.
These were copied from the gnulib git repository as of: commit 563c779682040ed4b89c9b4bbe428dcd8157c90a They come under the GNU GPL v3 (or later) exactly as notmuch is licensed.