rollback protobuf compiler to v3.20

Google went and broke JS support in v3.21. See: protocolbuffers/protobuf-javascript#127

Author: farrcraft

third_party/protoc/include/google/protobuf/any.proto renamed to third_party/protoc/win64/include/google/protobuf/any.proto

@@ -740,8 +740,8 @@ message UninterpretedOption {
   // The name of the uninterpreted option.  Each string represents a segment in
   // a dot-separated name.  is_extension is true iff a segment represents an
   // extension (denoted with parentheses in options specs in .proto files).
-  // E.g.,{ ["foo", false], ["bar.baz", true], ["moo", false] } represents
-  // "foo.(bar.baz).moo".
+  // E.g.,{ ["foo", false], ["bar.baz", true], ["qux", false] } represents
+  // "foo.(bar.baz).qux".
   message NamePart {
     required string name_part = 1;
     required bool is_extension = 2;
@@ -868,13 +868,13 @@ message SourceCodeInfo {
     //   // Comment attached to baz.
     //   // Another line attached to baz.
     //
-    //   // Comment attached to moo.
+    //   // Comment attached to qux.
     //   //
-    //   // Another line attached to moo.
-    //   optional double moo = 4;
+    //   // Another line attached to qux.
+    //   optional double qux = 4;
     //
     //   // Detached comment for corge. This is not leading or trailing comments
-    //   // to moo or corge because there are blank lines separating it from
+    //   // to qux or corge because there are blank lines separating it from
     //   // both.
     //
     //   // Detached comment for corge paragraph 2.

third_party/protoc/include/google/protobuf/api.proto renamed to third_party/protoc/win64/include/google/protobuf/api.proto

@@ -48,4 +48,5 @@ option cc_enable_arenas = true;
 //       rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty);
 //     }
 //
+// The JSON representation for `Empty` is empty JSON object `{}`.
 message Empty {}

third_party/protoc/include/google/protobuf/compiler/plugin.proto renamed to third_party/protoc/win64/include/google/protobuf/compiler/plugin.proto

@@ -1,12 +1,15 @@
 Protocol Buffers - Google's data interchange format
 Copyright 2008 Google Inc.
 https://developers.google.com/protocol-buffers/
+
 This package contains a precompiled binary version of the protocol buffer
 compiler (protoc). This binary is intended for users who want to use Protocol
 Buffers in languages other than C++ but do not want to compile protoc
 themselves. To install, simply place this binary somewhere in your PATH.
+
 If you intend to use the included well known types then don't forget to
 copy the contents of the 'include' directory somewhere as well, for example
 into '/usr/local/include/'.
+
 Please refer to our official github site for more installation instructions:
   https://github.com/protocolbuffers/protobuf