This rule will build each program, ignore all output, and return pass or
fail depending on whether the build has errors. This is helpful for
finding out which programs need to be fixed when a new Rust nightly
build inevitably breaks everything.
In the normal case, one does, e.g.,
make TEST="cat" test
This means that the value of EXES in the Makefile contains all
possible targets, which means many prerequisites that aren't
required get built.
With this change, when the `test` target is in effect (and,
in particular, *only* the test target), then the value of
EXES is ignored when calculating dependencies. Otherwise,
the values of EXES and TESTS are both considered.
With this change, individual submodules can specify their dependencies with
an additional file called "deps.mk" in the subdir. When building, only
the dependencies that are necessary are built, using cargo, and then linked.
This greatly simplifies adding new dependencies: add the package in
deps/Cargo.toml, and add the appropriate line in "deps.mk" in the
src/utilname/ directory, and the dependency will be built automatically
as needed.
This also removes the need to use git submodules.
After building the serialize crate, the rlib was copied to the build
directory using a hyphen in the library name ('librustc-serialize').
It seems that Rust expects an underscore instead.
This patch begins the work of modernizing uutils to work with 1.0-ish
Rust. In particular, it
1. Updates to the latest submodules.
2. Convert mkmain.rs, mkuutils.rs, and src/uutils/uutils.rs
to new slice syntax and use of new io, fs, and path APIs.
3. Convert src/common/util.rs to new io, fs, and path APIs.
4. Convert fmt to use new APIs.
