Resolve `perf-map-agent` directory better about perf-map-agent

[jrudolph]

Thanks for the suggestions. What kind of issues did you have?

The reason that PERF_FLAME_OUTPUT defaults to the current directory is that the output file is a "real product" of the call so I wouldn't want it to default to a possibly transient directory.

[nobeh]

I agree with the argument. Here is how I used the tool:

$ # clone the repo
$ # install
$ # did NOT create the symlinks
$ launch my app on a different term
$ cd /path/to/perf-map-agent
$ ./bin/perf-java-flames $PID

With the suggestions to resolve the real path of perf-map-agent, in the end, I got the result in root directory of perf-map-agent. I agree this is not critical and due to how I used the tool. However, I would also not want to pollute the git repo for perf-map-agent when using it.

Without the suggestions to resolve the real path of `perf-map-agent, I actually got an exception about failing to load the agent which makes sense because of how I used the tool.

[jrudolph]

I just found out that the script really was broken and it just worked for me before only because of an unclean work directory. I fixed it in the launcher script (adding the out directory) as you suggested and added extra diagnostic output to the Java attacher in case the library is missing.

Thanks for raising this issue.