protoc: "//nolint: gas" directive after pb generation (#164)

* protoc: "//nolint: gas" directive after pb generation

Fixes #138

Since we can't add package directives through the protoc
compiler, yet we need to "//nolint: gas" the Go generated
protobuf file, added a script whose purpose is to
go find the "package (\w+)$" declaration after go fmt
was run by protoc.

The competing solutions were more complex and can be
examined by visiting
https://github.com/tendermint/abci/issues/138#issuecomment-352226217

* simplify script

* rewrite script to work on Mac

Makefile

@@ -28,6 +28,9 @@ protoc:
 	##   ldconfig (may require sudo)
 	## https://stackoverflow.com/a/25518702
 	protoc $(INCLUDE) --gogo_out=plugins=grpc:. --lint_out=. types/*.proto
+	@echo "--> adding nolint declarations to protobuf generated files"
+	@awk '/package types/ { print "//nolint: gas"; print; next }1' types/types.pb.go > types/types.pb.go.new
+	@mv types/types.pb.go.new types/types.pb.go
 
 install:
 	@ go install ./cmd/...

types/types.pb.go

@@ -40,6 +40,7 @@ It has these top-level messages:
 	Evidence
 	KVPair
 */
+//nolint: gas
 package types
 
 import proto "github.com/gogo/protobuf/proto"