ci/alpine: use llvm variables

Fixes: da391650f5 ("ci: build a host version of mesa for cross builds")

Reviewed-by: Eric Engestrom <eric@igalia.com>
Signed-off-by: David Heidelberg <david@ixit.cz>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30482>

.gitlab-ci/container/alpine/x86_64_build.sh

@@ -18,7 +18,7 @@ DEPS=(
     bash
     bison
     ccache
-    clang16-dev
+    clang${LLVM_VERSION}-dev
     cmake
     clang-dev
     coreutils
@@ -31,8 +31,8 @@ DEPS=(
     glslang
     graphviz
     linux-headers
-    llvm16-static
-    llvm16-dev
+    llvm${LLVM_VERSION}-static
+    llvm${LLVM_VERSION}-dev
     meson
     mold
     musl-dev