multiple definition errors on GCC 10

It needs to be compiled with -fcommon on later GCC versions

/usr/bin/ld: ../../../lib/libDry.a(SDL_x11window.c.o):(.bss+0x30): multiple definition of `WAYLAND_wl_proxy_create'; ../../../lib/libDry.a(SDL_video.c.o):(.bss+0x30): first defined here
/usr/bin/ld: ../../../lib/libDry.a(SDL_x11window.c.o):(.bss+0x38): multiple definition of `WAYLAND_wl_proxy_marshal'; ../../../lib/libDry.a(SDL_video.c.o):(.bss+0x38): first defined here
/usr/bin/ld: ../../../lib/libDry.a(SDL_x11vulkan.c.o):(.bss+0x0): multiple definition of `WAYLAND_wl_proxy_get_user_data'; ../../../lib/libDry.a(SDL_video.c.o):(.bss+0x0): first defined here
/usr/bin/ld: ../../../lib/libDry.a(SDL_x11vulkan.c.o):(.bss+0x8): multiple definition of `WAYLAND_wl_proxy_set_user_data'; ../../../lib/libDry.a(SDL_video.c.o):(.bss+0x8): first defined here

I fixed this by disabling wayland:

cmake -D VIDEO_WAYLAND=OFF ..