Add nanopb-c support

Test: cd hardware/ril; mma
Change-Id: Id1481940d15a2a3f6eb29af54ee30080ff2286cb
diff --git a/android/config.go b/android/config.go
index 367b42c..50c1413 100644
--- a/android/config.go
+++ b/android/config.go
@@ -351,6 +351,10 @@
 
 var _ bootstrap.ConfigBlueprintToolLocation = (*config)(nil)
 
+func (c *config) HostToolPath(ctx PathContext, tool string) Path {
+	return PathForOutput(ctx, "host", c.PrebuiltOS(), "bin", tool)
+}
+
 // HostSystemTool looks for non-hermetic tools from the system we're running on.
 // Generally shouldn't be used, but useful to find the XCode SDK, etc.
 func (c *config) HostSystemTool(name string) string {