Though text formats aren't exactly fuzzer's strong suit, fuzzers can
catch many surface-level bugs.
The fuzz/ directory contains target programs, testcases and dictionaries
to drive the afl fuzzer.
This commit adds a fuzzer for the XKB keymap text format and the Compose
text format. On my slow machine, using a single core, a full cycle of
the XKB fuzzer takes 5 hours. For Compose, it takes a few minutes.
Fuzzing for the other file formats (rules files mostly) will be added
later.
To do some fuzzing, run `./fuzz/fuzz.sh`.
Signed-off-by: Ran Benita <ran234@gmail.com>