[glib: 1/2] gmemorymonitor: Mention malloc_trim() in the documentation

[Sebastian Dröge <sdroege src gnome org>]

commit 16c60289a441f895db3f7c5dcc56582378793f2a
Author: Philip Withnall <withnall endlessm com>
Date:   Mon Mar 9 18:30:58 2020 +0000

    gmemorymonitor: Mention malloc_trim() in the documentation
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    Fixes: #2057

 gio/gmemorymonitor.c | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/gio/gmemorymonitor.c b/gio/gmemorymonitor.c
index 4368ee3c5..ae0d3f7ce 100644
--- a/gio/gmemorymonitor.c
+++ b/gio/gmemorymonitor.c
@@ -47,6 +47,13 @@
  * - Run a garbage collection cycle
  * - Try and compress fragmented allocations
  * - Exit on idle if the process has no reason to stay around
+ * - Call [`malloc_trim(3)`](man:malloc_trim) to return cached heap pages to
+ *   the kernel (if supported by your libc)
+ *
+ * Note that some actions may not always improve system performance, and so
+ * should be profiled for your application. `malloc_trim()`, for example, may
+ * make future heap allocations slower (due to releasing cached heap pages back
+ * to the kernel).
  *
  * See #GMemoryMonitorWarningLevel for details on the various warning levels.
  *