I removed the diff'ing against which scripts Bro outputs as loaded
because that's going to be sensitive to changes in which scripts
get loaded by default. What really matters is the output that shows
that Bro was able to load the script via a directory's __load__.bro
Removed the test's diff against baseline output that contained absolute
paths so that it will work across systems. Also don't redirect anything
to stderr so that failure information shows up in btest diagnostic output.
With a directory "foo" somewhere in BROPATH, "@load foo" now checks if
there's a file "foo/__load__.bro". If so, it reads that file in. (If
not, Bro reports the same error as before, complaining that it can't
read a directory).
