meson: Add dependency on genxml to anvil

Currently the Intel "anvil" driver races with the generation of genxml
files, while i965 has an explicit dependency. This patch adds the same
dependency to anvil.

Fixes: d1992255
       ("meson: Add build Intel "anv" vulkan driver")
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
24 jobs for anv-gen-dep
Status Job ID Name Coverage
  Build+Test
canceled #115178
build:make-gallium-drivers-other

canceled #115177
build:make-gallium-drivers-radeonsi

canceled #115176
build:make-gallium-drivers-swr

canceled #115179
build:make-gallium-st-clover-llvm-39

canceled #115180
build:make-gallium-st-clover-llvm-4

canceled #115181
build:make-gallium-st-clover-llvm-5

canceled #115182
build:make-gallium-st-clover-llvm-6

canceled #115183
build:make-gallium-st-clover-llvm-7

canceled #115184
build:make-gallium-st-other

canceled #115175
build:make-loader-classic-dri

canceled #115174
build:make-vulkan

canceled #115170
build:meson-gallium-clover-llvm5

canceled #115171
build:meson-gallium-clover-llvm6

canceled #115172
build:meson-gallium-clover-llvm7

canceled #115169
build:meson-gallium-drivers-other

canceled #115168
build:meson-gallium-radeonsi

canceled #115173
build:meson-gallium-st-other

canceled #115167
build:meson-gallium-swr

canceled #115166
build:meson-glvnd

canceled #115165
build:meson-loader-classic-dri

canceled #115164
build:meson-vulkan

canceled #115186
build:scons-llvm

canceled #115185
build:scons-nollvm

canceled #115187
build:scons-swr