[RTE-475] Sync with upstream

[sardok]

The toolchain structure changed over the time. It changes from target directory contains all specific stdlib modules (like net, os, process etc) to stdlib modules directory contain target specific files.

Here are the notes taken during migration.

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In src/bootstrap:

• Add fortanixvme as target to be ignored by stage0 compiler.

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In compiler/rustc_target/src/spec/targets/x86_64_unknown_linux_fortanixvme.rs

• Added new TargetMetadata
• Synced data_layout of Fortanixvme target spec with musl target.

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In library/Cargo.toml files

• Added compiler_builtins as vsock (patched) uses it.

====
library/std

src/io/errors.rs:
io::ErrorKind::FilesystemQuotaExceeded -> io::ErrorKind::QuotaExceeded
io::const_io_error -> io::const_error

src/sys/args/unix.rs:
The interface of mod imp is changed. Now the mod imp expected to have
function with the following signature: pub fn argc_argv() -> (isize, *const *const c_char).
This function is called from pub fn args() free function within this module. Re-wrote the fortanixvme impl.

src/sys/net/connection/fortanixvme.rs:
This file is moved from src/sys/pal/unix/fortanixvme/net.rs.

Changelist:

• Added pub fn lookup_host(host: &str, port: u16) -> io::Result<LookupHost> function as required by src/net/socket_addr.rs.
  Implementation of it is on par with the relevant sgx implementation.
• TcpStream::connect, UdpStream::connect, TcpStream::bind, UdpStream::bind signature and implementation.
• Added fn each_addr<A: ToSocketAddrs, F, T>(addr: A, mut f: F) -> io::Result<T>.
  Implementation of it is on par with the relevant sgx implementation.
• Command::spawn in (src/sys/process/unix/unix.rs) requires Socket::new_pair in unix-like os.
  Added Socket::new_pair() (src/sys/net/connection/fortanixvme.rs). The implementation is extracted from
  src/sys/net/connection/unix.rs for linux target os.
• Removed io_err_to_addr because it is no longer needed with each_addr addition. Consequently, NonIpSockAddr::host is removed.
• LookupHost::port is removed.

src/sys/net/connection/socket

• Re-introduced TcpStream::read_buf.

src/net/tcp.rs

• Re-introduced TcpStream::read_buf.

Tests:

Disabled for fortanixvme target

• Disable tests/pipe_subprocess.rs (test level)
• Disable tests/process_spawning.rs (module level)
• Disable tests/switch-stdout.rs
• Disable src/io/copy/tests.rs (test level)