use defaults for GOPATH

Makefile

@@ -1,7 +1,6 @@
 SRC     := $(wildcard *.go) main/client.go
 BIN     := bin
 CLIENT  := ${BIN}/client
-GOPATH  ?= ${PWD}
 
 all: test client
 
@@ -9,10 +8,10 @@ client: ${CLIENT}
 
 ${CLIENT}: ${SRC}
 	@echo build $@
-	@GOPATH=${GOPATH} go build -o $@ -- main/client.go
+	go build -o $@ -- main/client.go
 
 test:
-	@GOPATH=${GOPATH} go test
+	go test
 
 clean:
 	@echo clean ${BIN}