Document reference commands and selective failures in the man page

Replace `println!` calls on the results paths with `writeln!` on
`io::stdout()` and propagate the `io::Error` to `main`, where
`ErrorKind::BrokenPipe` is turned into a quiet `exit(0)`. This matches
the conventional behavior of command-line tools when their output pipe
is closed early (e.g. `hyperfine ... | head -n 0`), and fixes panics in
all run-output paths: the per-benchmark header and results, the speed
comparison summary, and `-`-style exports to stdout. The warnings and
"Note" outputs to stderr are converted the same way.


---------

Co-authored-by: Mathjk <Mathjk@users.noreply.github.com>
Co-authored-by: David Peter <mail@david-peter.de>

.github/workflows/CICD.yml

@@ -79,6 +79,7 @@ jobs:
       matrix:
         job:
           - { target: aarch64-unknown-linux-gnu   , os: ubuntu-24.04, use-cross: true }
+          - { target: aarch64-unknown-linux-musl  , os: ubuntu-24.04, use-cross: true }
           - { target: arm-unknown-linux-gnueabihf , os: ubuntu-24.04, use-cross: true }
           - { target: arm-unknown-linux-musleabihf, os: ubuntu-24.04, use-cross: true }
           - { target: i686-pc-windows-msvc        , os: windows-2022                  }

doc/hyperfine.1

@@ -3,7 +3,8 @@
 hyperfine \- command\-line benchmarking tool
 .SH SYNOPSIS
 .B hyperfine
-.RB [ \-ihVN ]
+.RB [ \-hVN ]
+.RB [ \-\-ignore\-failure[=MODE] ]
 .RB [ \-\-warmup
 .IR NUM ]
 .RB [ \-\-min\-runs
@@ -14,6 +15,10 @@ hyperfine \- command\-line benchmarking tool
 .IR NUM ]
 .RB [ \-\-setup
 .IR CMD ]
+.RB [ \-\-reference
+.IR CMD ]
+.RB [ \-\-reference\-name
+.IR NAME ]
 .RB [ \-\-prepare
 .IR CMD ]
 .RB [ \-\-conclude
@@ -109,6 +114,16 @@ for compiling your software or with the provided parameters, or to do any
 other work that should happen once before a series of benchmark runs,
 not every time as would happen with the \fB\-\-prepare\fR option.
 .HP
+\fB\-\-reference\fR \fICMD\fP
+.IP
+Benchmark \fICMD\fP as the reference for the relative comparison of results.
+If this option is not specified, the fastest command is used as the reference.
+.HP
+\fB\-\-reference\-name\fR \fINAME\fP
+.IP
+Give a meaningful \fINAME\fP to the reference command.
+Requires \fB\-\-reference\fR.
+.HP
 \fB\-p\fR, \fB\-\-prepare\fR \fICMD...\fP
 .IP
 Execute \fICMD\fP before each timing run. This is useful for clearing disk caches,
@@ -207,9 +222,13 @@ things like "sleep 0.1; sleep 0.2" are not possible without a shell.
 .IP
 An alias for '\-\-shell=none'.
 .HP
-\fB\-i\fR, \fB\-\-ignore\-failure\fR
+\fB\-i\fR, \fB\-\-ignore\-failure\fR[=\fIMODE\fP]
 .IP
-Ignore non\-zero exit codes of the benchmarked programs.
+Ignore failures of the benchmarked programs. Without a value or with
+\fBall\-non\-zero\fR, all non\-zero exit codes are ignored.
+Alternatively, provide a comma\-separated list of exit codes to ignore,
+for example \fB\-\-ignore\-failure=1,2\fR.
+An explicit value must be attached to the option with an equals sign.
 .HP
 \fB\-\-style\fR \fITYPE\fP
 .IP