ci/alpine: install the real ninja package

The `samurai` re-implementation that we'd been using is missing the
tools, in particular `missingdeps` which we're about to start using, so
let's not leave alpine out.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37490>

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

@@ -42,6 +42,7 @@ DEPS=(
     "llvm${LLVM_VERSION}-static"
     mold
     musl-dev
+    ninja-build
     py3-clang
     py3-cparser
     py3-mako
@@ -50,7 +51,6 @@ DEPS=(
     py3-ply
     py3-yaml
     python3-dev
-    samurai
     spirv-llvm-translator-dev
     spirv-tools-dev
     util-macros
@@ -60,6 +60,10 @@ DEPS=(
 
 apk --no-cache add "${DEPS[@]}" "${EPHEMERAL[@]}"
 
+# shellcheck disable=2016  # we're not trying to evaluate $PATH now
+echo 'export PATH="/usr/lib/ninja-build/bin/:$PATH"' > /etc/profile.d/ninja-path.sh
+source /etc/profile.d/ninja-path.sh
+
 pip3 install --break-system-packages sphinx===8.2.3 hawkmoth===0.19.0
 
 . .gitlab-ci/container/container_pre_build.sh

.gitlab-ci/image-tags.yml

@@ -28,7 +28,7 @@ variables:
   DEBIAN_TEST_VIDEO_TAG: "20250813-vector"
   DEBIAN_TEST_VK_TAG: "20250930-piglit-a7"
 
-  ALPINE_X86_64_BUILD_TAG: "20250917-rust"
+  ALPINE_X86_64_BUILD_TAG: "20251001-realninja"
 
   FEDORA_X86_64_BUILD_TAG: "20250917-rust"