_get_glibc_version() can after #9005 return either (0, 0) if glibc
string is missing or (-1, -1) if the string can't be parsed. There was
no need to change missing string to (0, 0).
Also, move back indentation to make it easier to understand.
## Summary
On Termux, uv currently fails to find any interpreter because it can't
find a glibc version, because there isn't one. But the Python
interpreter is still functional nonetheless.
So, when glibc cannot be found, simply return 0 for the version numbers
and mark the interpreter as being incompatible with manylinux
I really don't know if this is the right way to address this, but I can
attest that manual testing shows uv appears to be fully functional, at
least for pip and virtualenvs.
Fixes#7373
## Test Plan
I tried running the test suite, and after some tweaks, a good portion of
the test suite passes as well. A significant number of tests fail, but
this appears to be due to minor differences in output, like warnings
about hard links not working (hard links are completely disallowed on
Android), differences in the number of files removed, etc. The test
suite seems to be very sensitive to minor variations in output.
Whew this is a lot.
The user-facing changes are:
- `uv toolchain` to `uv python` e.g. `uv python find`, `uv python
install`, ...
- `UV_TOOLCHAIN_DIR` to` UV_PYTHON_INSTALL_DIR`
- `<UV_STATE_DIR>/toolchains` to `<UV_STATE_DIR>/python` (with
[automatic
migration](https://github.com/astral-sh/uv/pull/4735/files#r1663029330))
- User-facing messages no longer refer to toolchains, instead using
"Python", "Python versions" or "Python installations"
The internal changes are:
- `uv-toolchain` crate to `uv-python`
- `Toolchain` no longer referenced in type names
- Dropped unused `SystemPython` type (previously replaced)
- Clarified the type names for "managed Python installations"
- (more little things)
