* Use `.format()` instead of `%` for constructing `make_commands`.
I'm about to add a third substitution parameter to these lines, and it's
already getting a bit crowded. This is a no-op change, but should make
the follow-up commits more readable.
* Add `make_toolchain` toolchain type.
Add a toolchain that implements it using the pre-installed system
`make`. Make use of this toolchain in the `make()` rule.
* Use the `make` toolchain in configure and cmake scripts as well.
This allows the registered `make` toolchain to be used not just in make,
but also in cmake and configure_make targets. As a result, one can
either ship their own `make`, built for the execution environment, or
use a custom `make`, e.g. one that calls `emmake make`.
To make this backwards compatible with `make_commands`, the substitution
will only replace the leading word `make` from any line in
`make_commands`. Thus, existing rules that specify a `make_commands`
attribute that refers to the binary simply as `make` should still work
with any toolchain implementation that provides the binary.
* Update `README.md`.
Describe the new toolchain type.
* Add `BootstrapMake` to bootstrap a `make` toolchain.
This allows the `make` toolchain to be used even without GNU Make being
pre-installed on the system.
* Add example Gnu Make boostrap target.
Test manually using:
```
$ cd examples
$ bazel build //build_make_itself:maketool
```
* Implement support for "pure" GNU Make in make.bzl
Usage: load("@rules_foreign_cc//tools/build_defs:make.bzl", "make")
make(name = <name>, lib_source = <source>), please see more arguments
in make.bzl
Add test in examples/simple_make (runs only on Linux because of Makefile contents)
