* Support --output for debug, trace, and test commands
With the `--output` parameter you can configure the output binary. For
example:
dlv debug --output /tmp/xxx
Will build the binary to `/tmp/xxx`, instead of always putting it as
`debug` in the current directory.
This ensures that the command always works (even if there is already a
file or directory named `debug`) and doesn't write to the source
directory. Especially for things like Delve/Vim integration this is a
good thing to have, I think.
* Address PR feedback and add a test
- We don't need to use `filepath.IsAbs()` on startup; I added that
because it previously did `"./" + debugname` everywhere, but I don't
think that's needed at all, since `pathname` without a leading `./`
implies the current directory.
- Repurpose the existing `TestIssue398` to also test the `--output`
flag. Also fix an issue where tests wouldn't work if `GOPATH` has
multiple entries (e..g `GOPATH=$HOME/go:$HOME/mygocode`).
- Print an error if we can't remove the debug binary on exit instead of
failing silently. Not strictly related to this PR, but a good change
to add I think.
* Also warn when delve can't remove the binary in test/trace
I only added that to debug, but good to issue this warning consistently.