mesa: disable Vulkan swrast + collision-proof CLOCK_MONOTONIC_RAW

On Redox relibc defines CLOCK_MONOTONIC=4 (not Linux 1) and has no
CLOCK_MONOTONIC_RAW, so -DCLOCK_MONOTONIC_RAW=4 collided with CLOCK_MONOTONIC in
wsi_common_wayland.c (duplicate case). The greeter uses GL/llvmpipe not Vulkan,
and Vulkan WSI is the only consumer of these Linux clock constants, so disable
vulkan-drivers to drop that unit. Also make the define collision-proof
(CLOCK_MONOTONIC+1000) for any non-Vulkan user.

local/recipes/libs/mesa/recipe.toml

@@ -96,9 +96,9 @@ cookbook_meson \
     -Dplatforms=wayland \
     -Degl-native-platform=surfaceless \
     -Dshader-cache=disabled \
-    -Dc_args="['-include','alloca.h','-DCLOCK_MONOTONIC_RAW=4','-Wno-error=implicit-function-declaration','-Wno-error=missing-prototypes','-Wno-error=return-type','-Wno-error=empty-body','-Wno-error=incompatible-pointer-types','-Wno-error=int-conversion','-Wno-error=format','-Wno-error','-std=gnu11','-Dstatic_assert=_Static_assert']" \
+    -Dc_args="['-include','alloca.h','-DCLOCK_MONOTONIC_RAW=(CLOCK_MONOTONIC+1000)','-Wno-error=implicit-function-declaration','-Wno-error=missing-prototypes','-Wno-error=return-type','-Wno-error=empty-body','-Wno-error=incompatible-pointer-types','-Wno-error=int-conversion','-Wno-error=format','-Wno-error','-std=gnu11','-Dstatic_assert=_Static_assert']" \
     -Dcpp_args="['-include','alloca.h','-Wno-error=implicit-function-declaration','-Wno-error=missing-prototypes','-Wno-error=return-type','-Wno-error=empty-body','-Wno-error=incompatible-pointer-types','-Wno-error=int-conversion','-Wno-error=format','-Wno-error']" \
-    -Dvulkan-drivers=swrast \
+    -Dvulkan-drivers= \
     -Dshared-glapi=enabled
 
 # Hack to add LLVM libs, the list can be seen from meson log and check for matches $("${LLVM_CONFIG}" --libs)