This fixes the build failure in Exiv2.
We recently added [inih](https://github.com/benhoyt/inih) as a
dependency to Exiv2, but we need a newer version of inih that includes
the C++ bindings. OSS-Fuzz is still using a docker image based on Ubuntu
20.04 which doesn't include a sufficiently up-to-date version of the
`libinih-dev` package. So I've added a build flag to Exiv2 in
https://github.com/Exiv2/exiv2/pull/2465 which enables us to build
without the inih dependency. The fuzz target doesn't need inih, so it
shouldn't make any difference to the fuzzing results.
Call exiv2's `install_dependencies.sh` script rather than using a
hard-coded list of packages. This should make the build less fragile
when we add new dependencies to exiv2. (Example:
https://github.com/Exiv2/exiv2/pull/2381.)
* Add Exiv2.
* Remove sanitizer flags so that OSS-Fuzz can insert its own.
* Using the fuzzer to create the seed corpus doesn't work with AFL.
* Only use libFuzzer
* Don't add files over 20KB to the corpus.
* Use ${LIB_FUZZING_ENGINE} when building the fuzz target.
Kevin Backhouse