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/etc/PROBLEMS b/etc/PROBLEMS
index 008f5a15310..9904339be40 100644
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -604,7 +604,7 @@ See <http://debbugs.gnu.org/22814>.
 When you have a large number of buffers running auto-revert-mode, and
 Emacs is configured to use the kqueue file notification library, it
 uses an own file descriptor for every watched file.  On systems with a
-small limit of file descriptors allowed per process, like OS X, you
+small limit of file descriptors allowed per process, like macOS, you
 could run out of file descriptors.  You won't be able to open new files.
 
 auto-revert-use-notify is set to nil in global-auto-revert-mode, therefore.