Protocol Buffers v21.8

Other

• Fix for grpc.tools #17995 & protobuf #7474 (handle UTF-8 paths in argumentfile) (#10721)

C++

• 21.x No longer define no_threadlocal on OpenBSD (#10743)

Java

• Mark default instance as immutable first to avoid race during static initialization of default instances (#10771)

Ruby

• Auto capitalize enums name in Ruby (#10454) (#10763)