meson: Allow to enable gtk and sdl while cocoa is enabled

As ui/cocoa does no longer override main(), ui/gtk and ui/sdl
can be enabled even ui/cocoa is enabled.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220819132756.74641-4-akihiko.odaki@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

meson.build

@@ -589,12 +589,6 @@ endif
 
 cocoa = dependency('appleframeworks', modules: ['Cocoa', 'CoreVideo'],
                    required: get_option('cocoa'))
-if cocoa.found() and get_option('sdl').enabled()
-  error('Cocoa and SDL cannot be enabled at the same time')
-endif
-if cocoa.found() and get_option('gtk').enabled()
-  error('Cocoa and GTK+ cannot be enabled at the same time')
-endif
 
 vmnet = dependency('appleframeworks', modules: 'vmnet', required: get_option('vmnet'))
 if vmnet.found() and not cc.has_header_symbol('vmnet/vmnet.h',
@@ -921,7 +915,7 @@ if not get_option('brlapi').auto() or have_system
 endif
 
 sdl = not_found
-if not get_option('sdl').auto() or (have_system and not cocoa.found())
+if not get_option('sdl').auto() or have_system
   sdl = dependency('sdl2', required: get_option('sdl'), kwargs: static_kwargs)
   sdl_image = not_found
 endif
@@ -1187,7 +1181,7 @@ endif
 gtk = not_found
 gtkx11 = not_found
 vte = not_found
-if not get_option('gtk').auto() or (have_system and not cocoa.found())
+if not get_option('gtk').auto() or have_system
   gtk = dependency('gtk+-3.0', version: '>=3.22.0',
                    method: 'pkg-config',
                    required: get_option('gtk'),