Document the M_ARENA_* mallopt parameters

The M_ARENA_* mallopt parameters are in wide use in production to
control the number of arenas that a long lived process creates and
hence there is no point in stating that this interface is non-public.
Document this interface and remove the obsolete comment.

	* manual/memory.texi (M_ARENA_TEST): Add documentation.
	(M_ARENA_MAX): Likewise.
	* malloc/malloc.c: Remove obsolete comment.

1 files changed, 4 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index ab8c4da4dd..1b21469ee5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2016-10-26  Siddhesh Poyarekar  <siddhesh@sourceware.org>
 
+	* manual/memory.texi (M_ARENA_TEST): Add documentation.
+	(M_ARENA_MAX): Likewise.
+	* malloc/malloc.c: Remove obsolete comment.
+
 	* manual/memory.texi: Add environment variable alternatives to
 	setting mallopt parameters.