FFmpeg, Android: Use llvm-readelf

In the current Android FFmpeg provisioning, we rely on the tool
'readelf' to be installed on the host. On macOS we currently pull this
tool through the Homebrew 'binutils' package. This has proven
unreliable on older macOS hosts.

The Android NDK provides the same tool under the name 'llvm-readelf'.
This patch makes us rely on this tool during provisioning, which is
guaranteed to be provided.

Change-Id: I47a186d2dd4b442929b82f35b4d257d011cb9d10
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
Reviewed-by: Dimitrios Apostolou <jimis@qt.io>
Reviewed-by: Tero Heikkinen <tero.heikkinen@qt.io>
(cherry picked from commit 07ec75fa35)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

coin/provisioning/common/unix/install-ffmpeg-android.sh

@@ -124,8 +124,14 @@ build_ffmpeg_android() {
         if [ $page_size == "use_16kb_page_size" ]; then
             page_size_arg="16384"
         fi
-
-        sudo "${fix_dependencies}" "${target_dir}" "${libs_prefix}" "no" "$page_size_arg"
+        local set_rpath_arg="no"
+        local readelf_path_arg="${toolchain_bin}/llvm-readelf"
+        sudo "$fix_dependencies" \
+            "$target_dir" \
+            "$libs_prefix" \
+            "$set_rpath_arg" \
+            "$page_size_arg" \
+            "$readelf_path_arg"
     fi
 }