test_unistd: Expand comments for skipping tests if not root

Author: JayH5

test/test_unistd.rs

@@ -107,8 +107,8 @@ mod linux_android {
 #[test]
 #[cfg(not(any(target_os = "ios", target_os = "macos")))]
 fn test_setgroups() {
+    // Skip this test when not run as root as `setgroups()` requires root.
     if !Uid::current().is_root() {
-        // setgroups() requires root
         return
     }
 
@@ -129,8 +129,9 @@ fn test_setgroups() {
 #[test]
 #[cfg(not(any(target_os = "ios", target_os = "macos")))]
 fn test_initgroups() {
+    // Skip this test when not run as root as `initgroups()` and `setgroups()`
+    // require root.
     if !Uid::current().is_root() {
-        // initgroups(), setgroups() require root
         return
     }