fix(git): add vendor in .gitignore

vendor/google.golang.org/grpc/Makefile

@@ -1,48 +0,0 @@
-all: vet test testrace
-
-build:
-	go build google.golang.org/grpc/...
-
-clean:
-	go clean -i google.golang.org/grpc/...
-
-deps:
-	GO111MODULE=on go get -d -v google.golang.org/grpc/...
-
-proto:
-	@ if ! which protoc > /dev/null; then \
-		echo "error: protoc not installed" >&2; \
-		exit 1; \
-	fi
-	go generate google.golang.org/grpc/...
-
-test:
-	go test -cpu 1,4 -timeout 7m google.golang.org/grpc/...
-
-testsubmodule:
-	cd security/advancedtls && go test -cpu 1,4 -timeout 7m google.golang.org/grpc/security/advancedtls/...
-	cd security/authorization && go test -cpu 1,4 -timeout 7m google.golang.org/grpc/security/authorization/...
-
-testrace:
-	go test -race -cpu 1,4 -timeout 7m google.golang.org/grpc/...
-
-testdeps:
-	GO111MODULE=on go get -d -v -t google.golang.org/grpc/...
-
-vet: vetdeps
-	./vet.sh
-
-vetdeps:
-	./vet.sh -install
-
-.PHONY: \
-	all \
-	build \
-	clean \
-	proto \
-	test \
-	testappengine \
-	testappenginedeps \
-	testrace \
-	vet \
-	vetdeps