mesa: consume native mesa-clc host tools (-Dmesa-clc=system -Dprecomp-compiler=system)

Add the mesa-clc dependency, put its staged usr/bin on PATH so meson's
find_program(native) resolves mesa_clc/vtn_bindgen2, and pass -Dmesa-clc=system
-Dprecomp-compiler=system. This resolves the cross-build structural error where
vtn_bindgen2 (native) linked target libs; with_clc now flips false so the cross
build no longer builds the in-tree CLC infra. Verified: cross mesa finds both
tools YES and passes every dependency + CLC gate (next blocker is the Redox
gallium winsys port).

local/recipes/libs/mesa/recipe.toml

@@ -46,6 +46,10 @@ dependencies = [
     "libwayland",
     "linux-kpi",
     "llvm21",
+    # Native host shader-precompile tools (mesa_clc, vtn_bindgen2) consumed via
+    # -Dmesa-clc=system -Dprecomp-compiler=system (the cross build can't run
+    # Redox target tools on the host).
+    "mesa-clc",
     # with_clc also links clang's C++ libraries: Mesa resolves clang via
     # cpp.find_library('clang-cpp', dirs: llvm-config --libdir), and the
     # llvm-config wrapper rewrites libdir to Mesa's target sysroot/lib. So the
@@ -118,7 +122,17 @@ else
     COOKBOOK_MESON_FLAGS+=(-Dshared-llvm=disabled)
 fi
 
+# The build-time shader compilers (mesa_clc, vtn_bindgen2) cannot be run as
+# Redox target binaries on the host, so we consume the natively-built host tools
+# from the mesa-clc dependency (staged into usr/bin) via -Dmesa-clc=system
+# -Dprecomp-compiler=system. Put them on PATH so meson's find_program(native)
+# resolves them. This also flips with_clc to false, so the cross build no longer
+# links the in-tree CLC infra (LLVMSPIRVLib/SPIRV-Tools/clang).
+export PATH="${COOKBOOK_SYSROOT}/usr/bin:${PATH}"
+
 cookbook_meson \
+    -Dmesa-clc=system \
+    -Dprecomp-compiler=system \
     -Ddri-drivers-path=/usr/lib/dri \
     -Degl=enabled \
     -Dgbm=enabled \