Fix build: Remove RocDecodeRuntimeLoader include from RocDecCache.h

After removing the runtime loader, RocDecCache.h still had the include
directive which caused build failures. The runtime loader is no longer
needed since we link rocdecode directly.

Also add install_rocdecode.sh packaging script following the same
pattern as install_rocjpeg.sh from PR meta-pytorch#1554.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: LakshmiKumar23

packaging/install_rocdecode.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# Installs the rocDecode library
+#
+# rocDecode is not preinstalled by default in the CI runners. Both the build
+# and the test jobs need it (we don't ship it in the wheel), so we install it
+# from the ROCm dnf repo.
+
+set -euo pipefail
+
+# rocDecode requires HIP runtime and other ROCm dependencies. On CI runners
+# with full ROCm, install from the repo directly. On build-only images that
+# lack the full amdgpu stack, install with --nodeps (dependencies are satisfied
+# by the ROCm environment used to build torch).
+install_rocdecode_build_only() {
+    dnf install -y "dnf-command(download)" >/dev/null 2>&1 || dnf install -y dnf-plugins-core
+    rpm_dir="$(mktemp -d)"
+    dnf download --destdir "${rpm_dir}" rocdecode rocdecode-devel
+    rpm -Uvh --nodeps "${rpm_dir}"/rocdecode*.rpm
+}
+
+dnf install -y --refresh rocdecode-devel \
+    || install_rocdecode_build_only

src/torchcodec/_core/RocDecCache.h

@@ -13,7 +13,6 @@
 #include <hip/hip_runtime.h>
 #include <torch/types.h>
 
-#include "RocDecodeRuntimeLoader.h"
 #include <rocdecode/rocdecode.h>
 #include <rocdecode/rocparser.h>