Modernize usage of 'macOS' in doc and comments

Apple changed the spelling of its operating system again, to "macOS",
effective with macOS 10.12 Sierra (2016-09-20).  Change Emacs
documentation and comments to match this.  Stick with older OS
spellings ("OS X", "Mac OS X") when talking about older releases where
the older names are more correct.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/gtkutil.c b/src/gtkutil.c
index 0f256c563dc..e323216bb79 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -2370,7 +2370,7 @@ make_widget_for_menu_item (const char *utf8_label, const char *utf8_key)
    in the group.  On exit, *GROUP contains the radio item group.
 
    Unfortunately, keys don't line up as nicely as in Motif,
-   but the MacOS X version doesn't either, so I guess that is OK.  */
+   but the macOS version doesn't either, so I guess that is OK.  */
 
 static GtkWidget *
 make_menu_item (const char *utf8_label,