bpo-35213: Where appropriate, use 'macOS' in idlelib. (#10478)


diff --git a/Lib/idlelib/iomenu.py b/Lib/idlelib/iomenu.py
index fcd8dcc..f5bced5 100644
--- a/Lib/idlelib/iomenu.py
+++ b/Lib/idlelib/iomenu.py
@@ -41,7 +41,7 @@
             # these problems, falling back to ASCII
             locale_encoding = locale.nl_langinfo(locale.CODESET)
             if locale_encoding is None or locale_encoding == '':
-                # situation occurs on Mac OS X
+                # situation occurs on macOS
                 locale_encoding = 'ascii'
             codecs.lookup(locale_encoding)
         except (NameError, AttributeError, LookupError):
@@ -51,7 +51,7 @@
             try:
                 locale_encoding = locale.getdefaultlocale()[1]
                 if locale_encoding is None or locale_encoding == '':
-                    # situation occurs on Mac OS X
+                    # situation occurs on macOS
                     locale_encoding = 'ascii'
                 codecs.lookup(locale_encoding)
             except (ValueError, LookupError):