closes#4682
The self-hosted compiler is still bit rotted and still not compiling
successfully yet. I have a more serious rework of the code in a
different branch.
This behaves the same as stdout and stderr behavior which also
default to .inherit. Also adds a field to RunStep to change the behavior.
Since this is a breaking change, previous behavior can be restored by doing:
`RunStep.stdin_behavior = .Ignore`.
Previously the zig build system incorrectly assumed that the only build
artifact was a binary. Now, when you enable the cache, only the output
dir is printed to stdout, and the zig build system iterates over the
files in that directory, copying them to the output directory.
To support this change:
* Add `std.os.renameat`, `std.os.renameatZ`, and `std.os.renameatW`.
* Fix `std.os.linux.renameat` not compiling due to typos.
* Deprecate `std.fs.updateFile` and `std.fs.updateFileMode`.
* Add `std.fs.Dir.updateFile`, which supports using open directory
handles for both the source and destination paths, as well as an
options parameter which allows overriding the mode.
* Update `std.fs.AtomicFile` to support operating based on an open
directory handle. Instead of `std.fs.AtomicFile.init`, use
`std.fs.Dir.atomicFile`.
* `std.fs.AtomicFile` deinit() better handles the situation when the
rename fails but the temporary file still exists, by still
attempting to remove the temporary file.
* `std.fs.Dir.openFileWindows` is moved to `std.os.windows.OpenFileW`.
* `std.os.RenameError` gains the error codes `NoDevice`,
`SharingViolation`, and `PipeBusy` which have been observed from
Windows.
Closes#4733
* `std.Buffer.print` is removed; use `buffer.outStream().print`
* `std.fmt.count` returns a `u64`
* `std.Fifo.print` is removed; use `fifo.outStream().print`
* `std.fmt.bufPrint` error is renamed from `BufferTooSmall`
to `NoSpaceLeft` to match `std.os.write`.
* `std.io.FixedBufferStream.getWritten` returns mutable buffer
if the buffer is mutable.
