Auto merge of #107405 - hermitcore:bsd, r=bjorn3

add support of RustyHermit's BSD socket layer

RustyHermit is a tier 3 platform and publishes a new kernel interface. The new version supports a common BSD socket layer. By supporting this interface, the implementation of `std` can be harmonized to other operating systems. In `sys_common/mod.rs` we remove only a special case for RustyHermit. All changes are done in the RustyHermit specific directories.

To realize this socket layer, the handling of file descriptors is also harmonized to other operating systems.