fix go build command line

[fenglyu]

vagrant@dev:/vagrant/libgraphqlparser/go$  go build
go: cannot find main module, but found .git/config in /vagrant/libgraphqlparser
        to create a module there, run:
        cd .. && go mod init
vagrant@dev:/vagrant/libgraphqlparser/go$ GO111MODULE="off" go build
vagrant@dev:/vagrant/libgraphqlparser/go$ ./go
field : myfield
Example error: 1.18-19: syntax error, unexpected on, expecting ( or @ or {

[linux-foundation-easycla]

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