Merge pull request #9488 An error occurred from muxi/advance-protoc-ver-3.1.0

Advance protoc version to 3.1.0

src/objective-c/!ProtoCompiler-gRPCPlugin.podspec

@@ -95,7 +95,7 @@ Pod::Spec.new do |s|
   s.preserve_paths = plugin
 
   # Restrict the protoc version to the one supported by this plugin.
-  s.dependency '!ProtoCompiler', '3.0.2'
+  s.dependency '!ProtoCompiler', '3.1.0'
   # For the Protobuf dependency not to complain:
   s.ios.deployment_target = '7.1'
   s.osx.deployment_target = '10.9'

src/objective-c/!ProtoCompiler.podspec

@@ -36,7 +36,7 @@ Pod::Spec.new do |s|
   # exclamation mark ensures that other "regular" pods will be able to find it as it'll be installed
   # before them.
   s.name     = '!ProtoCompiler'
-  v = '3.0.2'
+  v = '3.1.0'
   s.version  = v
   s.summary  = 'The Protobuf Compiler (protoc) generates Objective-C files from .proto files'
   s.description = <<-DESC