makefile: add the capability to build binarys separately (#1570)

* makefile: add the capability to build binarys separately

Makefile

@@ -35,15 +35,23 @@ dev: build check test
 
 ci: build check basic-test
 
-build: export GO111MODULE=on
-build:
+build: pd-server pd-ctl pd-tso-bench pd-recover
+pd-server: export GO111MODULE=on
+pd-server:
 ifeq ("$(WITH_RACE)", "1")
 	CGO_ENABLED=1 go build -race -ldflags '$(LDFLAGS)' -o bin/pd-server cmd/pd-server/main.go
 else
 	CGO_ENABLED=0 go build -ldflags '$(LDFLAGS)' -o bin/pd-server cmd/pd-server/main.go
 endif
+
+pd-ctl: export GO111MODULE=on
+pd-ctl:
 	CGO_ENABLED=0 go build -ldflags '$(LDFLAGS)' -o bin/pd-ctl tools/pd-ctl/main.go
+pd-tso-bench: export GO111MODULE=on
+pd-tso-bench:
 	CGO_ENABLED=0 go build -o bin/pd-tso-bench tools/pd-tso-bench/main.go
+pd-recover: export GO111MODULE=on
+pd-recover:
 	CGO_ENABLED=0 go build -o bin/pd-recover tools/pd-recover/main.go
 
 test: retool-setup