This commmit is a pure rename and does not change any functionality.
The `FLAG_` part of `ON_BROKEN_PIPE_FLAG_USED` comes from that the
compiler flag `-Zon-broken-pipe=...` is used to enable the feature.
Remove the `FLAG_` part so the name works both for the flag
`-Zon-broken-pipe=...` and for the upcoming Externally Implementable
Item `#[std::io::on_broken_pipe]`. This makes the diff of that PR
smaller.
The local variable name `sigpipe_attr_specified` comes from way back
when the feature was controlled with an `fn main()` attribute called
`#[unix_sigpipe = "..."]`. Rename that too.
Martin Nordholts
01c0c147c5