Macro cros_tracing::push_descriptors

macro_rules! push_descriptors {
    ($fd_vec:expr) => { ... };
}

Macro used to handle fd permanency across jailed devices. If we run crosvm without --disable-sandbox, we need to add the trace_marker file descriptor to the list of file descriptors allowed to be accessed by the sandboxed process. We call this macro to add the file descriptor to the list of keep_rds that the process is allowed to access every time we jail.