Avoid deprecation warning in NS-specific code

* src/macfont.m (mac_font_create_preferred_family_for_attributes):
CTGetCoreTextVersion is obsolete and its use elicits a warning
in macOS 11.6; use NSProcessInfo instead.

src/macfont.m

@@ -3570,7 +3570,10 @@ So we use CTFontDescriptorCreateMatchingFontDescriptor (no
 
       if (languages && CFArrayGetCount (languages) > 0)
         {
-          if (CTGetCoreTextVersion () >= kCTVersionNumber10_9)
+          if ([[NSProcessInfo processInfo]
+                isOperatingSystemAtLeastVersion:
+                  ((NSOperatingSystemVersion){
+                    .majorVersion = 10, .minorVersion = 9})])
             values[num_values++] = CFArrayGetValueAtIndex (languages, 0);
           else
             {