Merge PR #26237 into master

Merge PR #26237 into master

* refs/pull/26237/head:
	Revert "qa: update test_envlibrados_for_rocksdb.sh for libradospp split"
	doc/librados: explicitly mention that the C++ API is not stable
	ceph.spec: force use of upgrade devtoolset-gcc under RHEL 7
	librados: add symbol versioning to the C++ API
	librados: add symbol versioning to the C API
	librados: revert librados3/libradoscc back to librados2

Reviewed-by: Kefu Chai <kchai@redhat.com>