chat: fixing the chat Makefile to prevent it from removing source
files that are required by the chat tests

Change-Id: I382c97d632926e55a25a02abe6581f284100ae31
diff --git a/Makefile b/Makefile
index 623be30..a1bfa14 100644
--- a/Makefile
+++ b/Makefile
@@ -239,7 +239,7 @@
 
 clean:
 	rm -rf node_modules
-	rm -rf clients/shell/go/{bin,pkg,src/code.google.com,src/github.com,src/golang.org,src/v.io}
+	rm -rf clients/shell/go/{bin,pkg,src/code.google.com,src/github.com,src/golang.org}
 	rm -rf build
 	rm -rf vanadium.js