Fixes in 1990/jaw

The program (and the generated program made by shark.sh) no longer use
perror(3) and instead use fprintf(3) (writing to stderr). This is mostly
because in macOS errno == 0 looks like an error.

Some updates to the shark.sh script were also made.

The bug status has been updated as there is apparently another bug
though I was sure it was solved when I last looked at it. It happens
with and without the above updates. I'm unsure about other things too
but these are not in the bugs.md yet as I'm not even sure what to say
just yet.

Added try.sh script which does some of the commands. However as there is
that bug it doesn't do any comparisons - for now.

1990/jaw/try.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+echo "Running shark.sh:"
+sh shark.sh README.md jaw.c README.md > receive || exit 1
+echo "Done."
+
+echo "Attempting to extract files:"
+
+mkdir -p test
+cd test
+sh ../receive