Fix erroneous relative path resolution

[ivanvig]

Currently FuseSoC has two problems related to relative path resolution,

The more severe one occurs when the fusesoc.conf file is in the current directory, in that case the code

files_read = self._cp.read(config_files)

returns only the file name, then in the function _resolve_path_from_cfg when os.path.dirname is called, an empty string is returned and when joined to form the final path we get a broken result

A second issue that I found is when referencing to a relative path starting with a dot, for example ./build_root that dot stays in the path producing a result like /abs/path/to/./build_root which although is a valid path, fails path comparisons, like the ones that are done for ignored_dirs

This PR includes tests for both cases and fixes them.

[ivanvig]

@olofk could you take a look at this PR?

[olofk]

This looks like a nice cleanup of the paths, but the tests fail on macos. Could you take a look at the logs and see if you can figure out what potentially needs to be fixed?

[ivanvig]

It seems that realpath was adding a parent directory in macos which made the assertions fail, changed for normpath which does just what I wanted. I guess it should be fixed now, if it fails again I will get a macos docker image to run the tests.

[olofk]

Tests are passing now, so let's hope it stays that way. Thank you for your contributions. Picked and pushed!

[olofk]

Huh! Now it failed again? F-in inconstent Python. If you have some bandwidth to look at this, it would be highly appreciated.

[ivanvig]

Yep, I will look into it, I enabled the CI in my fork so I will test it there. It seems to be a problem related to how macos handles the /var directory, kinda annoying but it must be fixed.

[ivanvig]

Fixed in #731