Change format string %s -> %#v

Make go stop complaining about format string:
    "Errorf format %s has arg ba of wrong type"

Test: go test soong/...
Change-Id: I4615f5ff77e1c2c41b84fd227462cdb3564d4369

bazel/properties.go

@@ -492,7 +492,7 @@ func (ba *BoolAttribute) Collapse() error {
 		// Verify post-condition; this should never fail, provided no additional
 		// axes are introduced.
 		if len(ba.ConfigurableValues) > 1 {
-			panic(fmt.Errorf("error in collapsing attribute: %s", ba))
+			panic(fmt.Errorf("error in collapsing attribute: %#v", ba))
 		}
 	}
 	return nil