meson: fix Cocoa option in summary

Cocoa support was always shown as "no", even it if was enabled.

Fixes: b4e312e9 ("configure: move cocoa option to Meson")
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Chris Hofstaedtler <chris@hofstaedtler.name>
Message-Id: <20201230221623.60423-1-chris@hofstaedtler.name>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -2330,7 +2330,7 @@ summary_info += {'profiler':          config_host.has_key('CONFIG_PROFILER')}
 summary_info += {'link-time optimization (LTO)': get_option('b_lto')}
 summary_info += {'static build':      config_host.has_key('CONFIG_STATIC')}
 if targetos == 'darwin'
-  summary_info += {'Cocoa support': config_host.has_key('CONFIG_COCOA')}
+  summary_info += {'Cocoa support':   cocoa.found()}
 endif
 # TODO: add back version
 summary_info += {'SDL support':       sdl.found()}