all: increase minimum supported version to go1.9 (#742)

Author: dsnet

.travis.yml

@@ -1,7 +1,7 @@
 sudo: false
 language: go
 go:
-- 1.6.x
+- 1.9.x
 - 1.10.x
 - 1.11.x
 - 1.x

README.md

@@ -7,7 +7,7 @@ Google's data interchange format.
 Copyright 2010 The Go Authors.
 https://github.com/golang/protobuf
 
-This package and the code it generates requires at least Go 1.6.
+This package and the code it generates requires at least Go 1.9.
 
 This software implements Go bindings for protocol buffers.  For
 information about protocol buffers themselves, see

protoc-gen-go/grpc/grpc.go

@@ -52,7 +52,7 @@ const generatedCodeVersion = 4
 // Paths for packages used by code generated in this file,
 // relative to the import_prefix of the generator.Generator.
 const (
-	contextPkgPath = "golang.org/x/net/context"
+	contextPkgPath = "context"
 	grpcPkgPath    = "google.golang.org/grpc"
 )