Updating input framework unit tests.

Generally tried to make them more reliable and execute quicker.
They all now load the listen script as a trick to make sure input
sources are fully read, but also terminate() at appropriate times
so that they don't take more time than needed.  They're also all
serialized with the 'comm' group so listening on a port doesn't
interfere with the communication tests.

testing/btest/coverage/bare-mode-errors.test

@@ -5,6 +5,8 @@
 # Commonly, this test may fail if one forgets to @load some base/ scripts
 # when writing a new bro scripts.
 #
+# @TEST-SERIALIZE: comm
+#
 # @TEST-EXEC: test -d $DIST/scripts
 # @TEST-EXEC: for script in `find $DIST/scripts -name \*\.bro -not -path '*/site/*'`; do echo $script; if echo "$script" | egrep -q 'communication/listen|controllee'; then rm -rf load_attempt .bgprocs; btest-bg-run load_attempt bro -b $script; btest-bg-wait -k 2; cat load_attempt/.stderr >>allerrors; else bro -b $script 2>>allerrors; fi done || exit 0
 # @TEST-EXEC: cat allerrors | grep -v "received termination signal" | sort | uniq > unique_errors