Integrate nix::errno into Error.

Split sys/limits.rs; float dep:nix version.

Signed-off-by: Jason Volk <jason@zemos.net>

src/main/server.rs

@@ -51,7 +51,6 @@ pub fn new(args: Option<&Args>, runtime: Option<&runtime::Handle>) -> Result<Arc
 	#[cfg(feature = "sentry_telemetry")]
 	let sentry_guard = crate::sentry::init(&config);
 
-	#[cfg(unix)]
 	sys::maximize_fd_limit()
 		.expect("Unable to increase maximum soft and hard file descriptor limit");