Fix typo.

Change-Id: I85157a6b2056b6c17cae193200960b8cae3cb3b3
diff --git a/libc/private/bionic_atomic_arm.h b/libc/private/bionic_atomic_arm.h
index 3957d46..023d662 100644
--- a/libc/private/bionic_atomic_arm.h
+++ b/libc/private/bionic_atomic_arm.h
@@ -25,7 +25,7 @@
 #endif
 }
 
-/* Compare-and-swap, without any explicit barriers. Note that this functions
+/* Compare-and-swap, without any explicit barriers. Note that this function
  * returns 0 on success, and 1 on failure. The opposite convention is typically
  * used on other platforms.
  */