Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
* `!target`: cargo would reject `--target=<arch>`; in this case nailing-cargo's `-T` option is ineffective.
* `!target-dir`: cargo would reject `--target-dir`, so don't pass it. (Usually we pass `--target-dir=target` when we pass `--manifest-path`, since cargo's default is `target` in the same directory as `Cargo.toml`.)
+
There are also some properties which should not be needed, but are
provided for completeness. Do not use these to solve the problem
of nailing-cargo passing cargo options to a build command which is