env: ignoring SIGPIPE not working

[Ecordonnier]

After #9614 there is a regression in env: ignoring SIGPIPE doesn't work any more, because the rust implementation of Command::exec() resets the SIGPIPE signal handler to its default handler (see https://github.com/rust-lang/rust/blob/c61a3a44d1a5bee35914cada6c788a05e0808f5b/library/std/src/sys/process/unix/unix.rs#L368 ).

This will be fixed in rust at some point ( see rust-lang/rust#97889 (comment) , rust-lang/rust#62569 , etc.) however with current stable rust version there is no way to make it work with Command::exec().

#9614 needs to be reverted, and a regression-tests added.

See also #8919 which is related

[ChrisDryden]

I've been doing a bunch of experimentation on how to get this working and building on the work that @mattsu2020 did in seq to create the ability to handle the ignored signal. I created a handler in the signals library and worked on applying it to see if it could be used to pass every signals related GNU test and it appears it is able to work for all of the use cases.https://github.com/uutils/coreutils/pull/9646/changes#diff-0cb7b16878f5d3cd1c3e444e45a4b09c151b450c98f227ec29c197cc75ca2f5f

While working on the fixes I found that not only do we need to use a workaround like this for getting the ignore pipeline signal but we also need it to know that if the stdout and stderr are in a bad state when the program is initialized since we need to be able to handle /dev/null and a closed fd differently and rust points all closed fd's to /dev/null, but this can be handled in the same way that we can handle saving the state of if the pipeline signal is ignored.

[ChrisDryden]

For this I have one PR that implements the signal handler for seq: #9657

To be able to use the env ignore SIGPIPE I also added the missing options in ENV here: #9658. There is an additional GNU test that passes once both of these are in