ui/cocoa: Interpret left button down as is when command is pressed

ui/cocoa: Interpret left button down as is when command is pressed

Old Macs were not equipped with mice with an ability to perform
"right clicks" and ui/cocoa interpreted left button down with
left command key pressed as right button down as a workaround.

The workaround has an obvious downside: you cannot tell the guest
that the left button is down while the left command key is
pressed.

Today, Macs has trackpads, Apple Mice, or Magic Mice. They are
capable to emulate right clicks with gestures, which also allows
to perform right clicks on "BootCamp" OSes like Windows.

By removing the workaround, we overcome its downside, and provide
a behavior consistent with BootCamp.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Message-Id: <20210212000706.28616-1-akihiko.odaki@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>