cmake: fix build with SDL_WAYLAND_SHARED=OFF

(cherry-picked from commit 711846c1f4be660f106b1bc1ccbe8e5b824c30d7)

CMakeLists.txt

@@ -483,7 +483,7 @@ endforeach()
 set_option(SDL_WAYLAND             "Use Wayland video driver" ${UNIX_SYS})
 dep_option(SDL_WAYLAND_SHARED      "Dynamically load Wayland support" ON "SDL_WAYLAND" OFF)
 dep_option(SDL_WAYLAND_LIBDECOR    "Use client-side window decorations on Wayland" ON "SDL_WAYLAND" OFF)
-dep_option(SDL_WAYLAND_LIBDECOR_SHARED     "Dynamically load libdecor support" ON "SDL_WAYLAND_LIBDECOR" OFF)
+dep_option(SDL_WAYLAND_LIBDECOR_SHARED     "Dynamically load libdecor support" ON "SDL_WAYLAND_LIBDECOR;SDL_WAYLAND_SHARED" OFF)
 dep_option(SDL_WAYLAND_QT_TOUCH    "QtWayland server support for Wayland video driver" ON "SDL_WAYLAND" OFF)
 set_option(SDL_RPI                 "Use Raspberry Pi video driver" ${UNIX_SYS})
 set_option(SDL_COCOA               "Use Cocoa video driver" ${APPLE})