Since Musl is sufficiently different from Glibc (see https://wiki.musl-libc.org/functional-differences-from-glibc.html), it requires a different import, which now should be applied to files that have `import Glibc` in them.
Musl is a low footprint libc that's used in Linux distributions such as Alpine Linux, which allows producing fairly small container images. Additionally, unlike Glibc, musl allows full static linking, meaning apps can be easily distributed to an arbitrary Linux distribution that may have a version of Glibc incompatible with the one that Swift is usually built with or no Glibc installed at all.
We receive a `SIGPIPE` if we write to a pipe that points to a crashed process. This in particular happens if the target of a `JSONRPCConnection` has crashed and we try to send it a message.
On Darwin, `DispatchIO` ignores `SIGPIPE` for the pipes handled by it, but that features is not available on Linux.
Instead, globally ignore `SIGPIPE` on Linux to prevent us from crashing if the `JSONRPCConnection`'s target crashes.
Fixes rdar://75580936
