vulkan/wsi/wayland: Move Wayland protocol from BUILT_SOURCES

vulkan/wsi/wayland: Move Wayland protocol from BUILT_SOURCES

autotools wants to have the BUILT_SOURCES ready as soon as it enters the
directory, even if they are not used. This meant the build failed if
wayland-protocols was not available on the system, even if it was not
enabled.

As BUILT_SOURCES cannot be used in a conditional (cf. 166852ee957f), do
the same thing as EGL and manually encode the dependencies in the
Makefile.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Fixes: bfa22266cd4d ("vulkan/wsi/wayland: Add support for zwp_dmabuf")
Cc: Emil Velikov <emil.velikov@collabora.co.uk>
Reported-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105211