Modify the wording of the mallopt.

The original wording implies that memory tagging can be disabled
per thread. That is not really possible, and doesn't happen. Instead,
this option only turns off some of the memory tagging initialization.
Leave this slightly vague since it's possible this might change
in the future.

Bug: 272383932

Test: NA
Change-Id: I6333f16175edb52a38aadfc67ce7c9ce76113e59
diff --git a/libc/include/malloc.h b/libc/include/malloc.h
index 6a2d380..91d63b3 100644
--- a/libc/include/malloc.h
+++ b/libc/include/malloc.h
@@ -232,8 +232,9 @@
 /**
  * mallopt() option for per-thread memory initialization tuning.
  * The value argument should be one of:
- * 1: Disable automatic heap initialization and, where possible, memory tagging,
- *    on this thread.
+ * 1: Disable automatic heap initialization on this thread only.
+ *    If memory tagging is enabled, disable as much as possible of the
+ *    memory tagging initialization for this thread.
  * 0: Normal behavior.
  *
  * Available since API level 31.