[gobject-introspection] gir: Update annotations from glib git master

[Rico Tzschichholz <ricotz src gnome org>]

commit 869bbfa6f47d128946313a8518a54ec085439a70
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Thu Feb 4 19:41:30 2021 +0100

    gir: Update annotations from glib git master

 gir/glib-2.0.c    | 29 +++++++++++++++++++++++++----
 gir/gobject-2.0.c |  5 +++--
 2 files changed, 28 insertions(+), 6 deletions(-)
---
diff --git a/gir/glib-2.0.c b/gir/glib-2.0.c
index 6d643089..465a4f6a 100644
--- a/gir/glib-2.0.c
+++ b/gir/glib-2.0.c
@@ -20117,7 +20117,7 @@
  * g_key_file_get_comment:
  * @key_file: a #GKeyFile
  * @group_name: (nullable): a group name, or %NULL
- * @key: a key
+ * @key: (nullable): a key
  * @error: return location for a #GError
  *
  * Retrieves a comment above @key from @group_name.
@@ -23863,6 +23863,23 @@
  */
 
 
+/**
+ * g_memdup2:
+ * @mem: (nullable): the memory to copy.
+ * @byte_size: the number of bytes to copy.
+ *
+ * Allocates @byte_size bytes of memory, and copies @byte_size bytes into it
+ * from @mem. If @mem is %NULL it returns %NULL.
+ *
+ * This replaces g_memdup(), which was prone to integer overflows when
+ * converting the argument from a #gsize to a #guint.
+ *
+ * Returns: (nullable): a pointer to the newly-allocated copy of the memory,
+ *    or %NULL if @mem is %NULL.
+ * Since: 2.68
+ */
+
+
 /**
  * g_memmove:
  * @dest: the destination address to copy the bytes to.
@@ -33960,8 +33977,12 @@
  * behaviour, to verify that appropriate warnings are given. It might, in some
  * cases, be useful to turn this off with if running tests under valgrind;
  * in tests that use g_test_init(), the option `-m no-undefined` disables
- * those tests, while `-m undefined` explicitly enables them (the default
- * behaviour).
+ * those tests, while `-m undefined` explicitly enables them (normally
+ * the default behaviour).
+ *
+ * Since GLib 2.68, if GLib was compiled with gcc or clang and
+ * [AddressSanitizer](https://github.com/google/sanitizers/wiki/AddressSanitizer)
+ * is enabled, the default changes to not exercising undefined behaviour.
  *
  * Returns: %TRUE if tests may provoke programming errors
  */
@@ -36736,7 +36757,7 @@
  * be a scope ID attached to the address. Eg, `fe80::1234%``em1` (or
  * `fe80::1234%``25em1` if the string is still encoded).
  *
- * Returns: (not nullable): @uri's host.
+ * Returns: (nullable): @uri's host.
  * Since: 2.66
  */
 
diff --git a/gir/gobject-2.0.c b/gir/gobject-2.0.c
index 703c20e1..eaecc72d 100644
--- a/gir/gobject-2.0.c
+++ b/gir/gobject-2.0.c
@@ -1887,6 +1887,7 @@
  * g_clear_signal_handler:
  * @handler_id_ptr: A pointer to a handler ID (of type #gulong) of the handler to be disconnected.
  * @instance: (type GObject.Object): The instance to remove the signal handler from.
+ *   This pointer may be %NULL or invalid, if the handler ID is zero.
  *
  * Disconnects a handler from @instance so it will not be called during
  * any future or currently ongoing emissions of the signal it has been
@@ -1894,8 +1895,8 @@
  *
  * If the handler ID is 0 then this function does nothing.
  *
- * A macro is also included that allows this function to be used without
- * pointer casts.
+ * There is also a macro version of this function so that the code
+ * will be inlined.
  *
  * Since: 2.62
  */