demo-rockylinux build is experiencing configure failures building pkgconf

```
Step #0 - "kaniko-build": time="2025-12-10T18:37:17Z" level=info msg="WORKDIR /var/tmp/build/pkgconf"
Step #0 - "kaniko-build": time="2025-12-10T18:37:17Z" level=info msg="Cmd: workdir"
Step #0 - "kaniko-build": time="2025-12-10T18:37:17Z" level=info msg="Changed working directory to /var/tmp/build/pkgconf"
Step #0 - "kaniko-build": time="2025-12-10T18:37:17Z" level=info msg="Creating directory /var/tmp/build/pkgconf with uid -1 and gid -1"
Step #0 - "kaniko-build": time="2025-12-10T18:37:17Z" level=info msg="Taking snapshot of files..."
Step #0 - "kaniko-build": time="2025-12-10T18:37:17Z" level=info msg="RUN curl -fsSL https://distfiles.ariadne.space/pkgconf/pkgconf-2.2.0.tar.gz | tar -xzf - --strip-components=1 && ./configure --prefix=/usr --with-system-libdir=/lib64:/usr/lib64 --with-system-includedir=/usr/include && make -j ${NCPU:-4} && make install && ldconfig && cd /var/tmp && rm -fr build"
Step #0 - "kaniko-build": time="2025-12-10T18:37:17Z" level=info msg="Initializing snapshotter ..."
Step #0 - "kaniko-build": time="2025-12-10T18:37:17Z" level=info msg="Taking snapshot of full filesystem..."
Step #0 - "kaniko-build": time="2025-12-10T18:37:22Z" level=info msg="Cmd: /bin/sh"
Step #0 - "kaniko-build": time="2025-12-10T18:37:22Z" level=info msg="Args: [-c curl -fsSL https://distfiles.ariadne.space/pkgconf/pkgconf-2.2.0.tar.gz | tar -xzf - --strip-components=1 && ./configure --prefix=/usr --with-system-libdir=/lib64:/usr/lib64 --with-system-includedir=/usr/include && make -j ${NCPU:-4} && make install && ldconfig && cd /var/tmp && rm -fr build]"
Step #0 - "kaniko-build": time="2025-12-10T18:37:22Z" level=info msg="Running: [/bin/sh -c curl -fsSL https://distfiles.ariadne.space/pkgconf/pkgconf-2.2.0.tar.gz | tar -xzf - --strip-components=1 && ./configure --prefix=/usr --with-system-libdir=/lib64:/usr/lib64 --with-system-includedir=/usr/include && make -j ${NCPU:-4} && make install && ldconfig && cd /var/tmp && rm -fr build]"
Step #0 - "kaniko-build": checking for gcc... no
Step #0 - "kaniko-build": checking for cc... no
Step #0 - "kaniko-build": checking for cl.exe... no
Step #0 - "kaniko-build": checking for clang... no
Step #0 - "kaniko-build": configure: error: in `/var/tmp/build/pkgconf':
Step #0 - "kaniko-build": configure: error: no acceptable C compiler found in $PATH
Step #0 - "kaniko-build": See `config.log' for more details
Step #0 - "kaniko-build": error building image: error building stage: failed to execute command: waiting for process to exit: exit status 1
```

失敗は、pkgconf-2.2.0 の設定中に demo-rockylinux イメージ用の Kaniko ビルドコマンドで発生しています。まずイメージのビルド定義とその toolchain の依存関係を調査し、その後 configure ステップを再現してください。イメージのビルドが「no acceptable C compiler found」エラーなしで configure を通過すれば完了です。

索引モデルが issue の本文から書いたものです。