add src/ suffix to VDLPATH

Addresses https://github.com/vanadium/issues/issues/145.

MultiPart: 5/6
Change-Id: Ifc92539e6e939beb7d05f532ef54401f409979f7
diff --git a/go/src/v.io/x/playground/Dockerfile b/go/src/v.io/x/playground/Dockerfile
index 36f9b6d..4e81e3f 100644
--- a/go/src/v.io/x/playground/Dockerfile
+++ b/go/src/v.io/x/playground/Dockerfile
@@ -13,7 +13,7 @@
 ENV HOME /root
 ENV V23_ROOT /usr/local/vanadium
 ENV GOPATH $V23_ROOT/release/projects/playground/go
-ENV VDLPATH $GOPATH
+ENV VDLPATH $V23_ROOT/release/projects/playground/go/src
 ENV PATH $V23_ROOT/release/projects/playground/go/bin:$V23_ROOT/release/go/bin:$V23_ROOT/devtools/bin:$PATH
 
 # Setup Vanadium.
diff --git a/go/src/v.io/x/playground/Makefile b/go/src/v.io/x/playground/Makefile
index ac5f495..bfe8309 100644
--- a/go/src/v.io/x/playground/Makefile
+++ b/go/src/v.io/x/playground/Makefile
@@ -1,7 +1,7 @@
 PATH := $(V23_ROOT)/release/projects/playground/go/bin:$(PATH)
 SHELL := /bin/bash -euo pipefail
 export GOPATH := $(V23_ROOT)/release/projects/playground/go:$(GOPATH)
-export VDLPATH := $(GOPATH)
+export VDLPATH := $(V23_ROOT)/release/projects/playground/go/src:$(VDLPATH)
 
 host ?= 127.0.0.1
 port ?= 8181
diff --git a/go/src/v.io/x/playground/builder/main.go b/go/src/v.io/x/playground/builder/main.go
index 908d5c1..e9dee17 100644
--- a/go/src/v.io/x/playground/builder/main.go
+++ b/go/src/v.io/x/playground/builder/main.go
@@ -218,7 +218,7 @@
 		return true, nil
 	}
 	os.Setenv("GOPATH", pwd+":"+os.Getenv("GOPATH"))
-	os.Setenv("VDLPATH", pwd+":"+os.Getenv("VDLPATH"))
+	os.Setenv("VDLPATH", pwd+"/src:"+os.Getenv("VDLPATH"))
 	// We set isService=false for compilation because "go install" only produces
 	// output on error, and we always want clients to see such errors.
 	// TODO(ivanpi): We assume *exec.ExitError results from uncompilable input