Fix compile-fail error message

Author: Aaron1011

tests/compile-fail/getrandom.rs

@@ -8,6 +8,6 @@ fn main() {
     let mut buf = [0u8; 5];
     unsafe {
         libc::syscall(libc::SYS_getrandom, buf.as_mut_ptr() as *mut libc::c_void, 5 as libc::size_t, 0 as libc::c_uint);
-        //~^ ERROR constant evaluation error: miri does not support random number generators in deterministic mode!
+        //~^ ERROR constant evaluation error: miri does not support gathering system entropy in deterministic mode!
     }
 }