openvino: bundle abseil for protobufmain

Configuring 2026.4.0 failed with "The source directory
thirdparty/protobuf/protobuf/third_party/abseil-cpp does not contain a
CMakeLists.txt file". The protobuf commit this tag pins is 5.26.0,
where the old one was 3.21, and 5.26.0 builds utf8_range, which pulls
abseil in as a nested submodule of its own. Like every other submodule
here it ships as an empty placeholder directory.

Pinned to the abseil commit that protobuf commit references, and
unpacked after protobuf so the path it goes into exists.

The system protobuf cannot be used instead: openvino asks
find_package for 5.26.0, and protobuf's cmake config only accepts a
matching major, so Slackware's 36.1 is rejected rather than treated as
newer.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions