This was brought up as something that would be useful by
`RealKC` on the discord, and I happened to agree that it
would be useful. Especially given the abundance of Toolchain
changes recently.
This change fixes two bugs:
1) If you run `serenity.sh` outside of your serenity git clone, the
`get_top_dir()` function won't be able to auto detect the serenity
root dir and we'll error out. By allowing the script to use an
existing $SERENITY_ROOT vlaue if it exists, we can solve
this problem.
2) If tried to run a command which ends up calling `build_toolchain()`
and you were outside of the root of the project, it should just
fail. Fix this by utilizing `$SERENITY_ROOT`.
I have this symlinked into ~/bin, when looking at the help/usage
it would previously print the fully qualified path to the script
making the help very difficult to read.
Running the tests will be moved to a separate test command which can
then leverage the availability of different targets and run either unit
tests on the host or the image in QEMU in self-test mode. :^)
- Only call ensure_toolchain for non-lagom targets
- Use host addr2line, we can't expect the i686 toolchain's addr2line to
support the host's binary executable format
- Don't export SERENITY_ARCH and TOOLCHAIN_DIR, don't need them anymore
