fix maxrss compute for mac in print_step_rusage

gistfile1.txt

commit 7126619a396191a8789367458ca9d4273f458672 (HEAD -> fix-max-rss-division-on-mac)
Author: Felix Klock <[email protected]>
Date:   Fri May 21 10:31:39 2021 -0400

    facepalm: operator precedence fail on my part.
    
    This bug was only visible on mac. Also, print_step_rusage is a
    relatively new internal feature, that is not heavily used, and has no
    tests. All of these factors contributed to how this went uncaught this
    long. Thanks to Josh Triplett for pointing it out!

diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index d462dc4d116..4b98abfb308 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -305,7 +305,7 @@ fn format_rusage_data(_child: Child) -> Option<String> {
     };
     // Mac OS X reports the maxrss in bytes, not kb.
     let divisor = if env::consts::OS == "macos" { 1024 } else { 1 };
-    let maxrss = rusage.ru_maxrss + (divisor - 1) / divisor;
+    let maxrss = (rusage.ru_maxrss + (divisor - 1)) / divisor;
 
     let mut init_str = format!(
         "user: {USER_SEC}.{USER_USEC:03} \