bug#29199: 26.0.90; Emacs 25 and 26 branches no longer build on Mac

[John Wiegley]

I'm seeing these failures, which appear to have been introduced by
455fe1a7f1cf5cf6b7f1fc99bb8b05c633503c1d.

John

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macfont.m:1023:42: error: unknown type name 'CFNotificationCenterRef'; did you 
mean 'NSNotificationCenter'?
macfont_handle_font_change_notification (CFNotificationCenterRef center,
                                         ^~~~~~~~~~~~~~~~~~~~~~~
                                         NSNotificationCenter
/nix/store/hxl2i2wbknvj7rcz0xnxfbpq432z79s3-apple-framework-AppKit/Library/Frameworks/AppKit.framework/Headers/NSWorkspace.h:13:43:
 note: 'NSNotificationCenter' declared here
@class NSArray, NSError, NSImage, NSView, NSNotificationCenter, NSURL, 
NSScreen, NSRunningApplication;
                                          ^
macfont.m:1023:66: error: interface type 'NSNotificationCenter' cannot be 
passed by value; did you forget * in 'NSNotificationCenter'?
macfont_handle_font_change_notification (CFNotificationCenterRef center,
                                                                 ^
                                                                *
macfont.m:1041:3: warning: implicit declaration of function 
'CFNotificationCenterAddObserver' is invalid in C99 
[-Wimplicit-function-declaration]
  CFNotificationCenterAddObserver
  ^
macfont.m:1042:6: warning: implicit declaration of function 
'CFNotificationCenterGetLocalCenter' is invalid in C99 
[-Wimplicit-function-declaration]
    (CFNotificationCenterGetLocalCenter (), NULL,
     ^
macfont.m:1045:12: error: use of undeclared identifier 
'CFNotificationSuspensionBehaviorCoalesce'; did you mean 
'NSNotificationSuspensionBehaviorCoalesce'?
     NULL, CFNotificationSuspensionBehaviorCoalesce);
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           NSNotificationSuspensionBehaviorCoalesce
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