* remove fetching seeds from my corpus, fetch instead from src repo
* conditionally zip up fuzzer seed corpora for any fuzzer passed in
* Simplify build steps
We already know that the fuzzers are being iterated over due to the loop
and globbing. As such, we can use more of the fuzzer name and reduce
repetition. This should allow us to add fuzzers/corpora to the src repo
and no need to change anything about the build script or dockerfile
Chris Wolfe