Sort the C files before processing them
Sort the C files before processing them

Otherwise they are parsed in random order and running clay on an
unchanged source tree produces changes in the generated files, and a
lot of noise is produced in the diff when adding tests.

Signed-off-by: Carlos Martín Nieto <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@cmartin.tk>

ethomson/clar,carlosmn/clar,carlosmn/clar,vmg/clar,ethomson/clar,carlosmn/clar,vmg/clar