fixup to Disable the libc::personality doc test on QEMU

Author: asomers

src/sys/personality.rs

@@ -54,7 +54,8 @@ libc_bitflags! {
 ///
 /// Example:
 ///
-/// ```
+#[cfg_attr(any(qemu, target_arch = "aarch64"), doc = " ```no_run")]
+#[cfg_attr(not(any(qemu, target_arch = "aarch64")), doc = " ```")]
 /// # use nix::sys::personality::{self, Persona};
 /// let pers = personality::get().unwrap();
 /// assert!(!pers.contains(Persona::WHOLE_SECONDS));