* gnu/packages/protobuf.scm (protobuf): Update to 3.21.9. Move outputs field before
build system. Move inputs field below arguments.
[source]: Apply patch and update URL.
[build-system]: Use cmake-build-system. This causes the CMake support files
to be installed, which is expected by some packages such as hyperledger-iroha.
[arguments]: Use gexps.
[configure-flags]: Add BUILD_SHARED_LIBS=ON.
[phases]: Add set-c++-standard.
[home-page]: Update URL.
(protobuf-3.6): Adjust to continue using the gnu-build-system.
* gnu/packages/patches/protobuf-fix-build-on-32bit.patch: New patch.
* gnu/local.mk (dist_patch_DATA): Register it.
9f6479ecad