"core/veyron/tools": Test must run under agent

This Part 2 of a series of changes to make go tests self-contained
and in particular run under an agent.
See: https://vanadium-review.googlesource.com/#/c/1931/

Change-Id: I956a15d7612e16d369c5b4882fa413c7c62aed04
diff --git a/tools/binary/impl_test.go b/tools/binary/impl_test.go
index 8d19bbd..d0f7ca6 100644
--- a/tools/binary/impl_test.go
+++ b/tools/binary/impl_test.go
@@ -22,6 +22,7 @@
 	"v.io/core/veyron2/services/security/access"
 	"v.io/core/veyron2/vlog"
 
+	tsecurity "v.io/core/veyron/lib/testutil/security"
 	"v.io/core/veyron/profiles"
 )
 
@@ -126,6 +127,9 @@
 	}
 	defer runtime.Cleanup()
 	gctx = runtime.NewContext()
+	if gctx, err = veyron2.SetPrincipal(gctx, tsecurity.NewPrincipal("test-blessing")); err != nil {
+		panic(err)
+	}
 
 	server, endpoint, err := startServer(t, gctx)
 	if err != nil {