Go Maps for Thrift Sets Should Have Values of Type struct{}

Sets in Thrift are currently turned into maps with boolean values in Go. Example:

Thrift

namespace go bug
service FooService{
	void bar (1:set<string> foos)
}

Go

func (p *FooServiceClient) Bar(foos map[string]bool) (err error) 

Boolean map values waste memory. Map values should be of the zero-byte struct{} type.