Add product_available to product available modules

vendor_available modules were available to product modules.
However, not all vendor_available modules are required to be
available to product modules. Some modules want to be available only
to product modules but not vendor modules.

To cover the requirement, we separate product_available from
vendor_available.
vendor_available will not provide product available module.

Bug: 150902910
Test: build
Change-Id: I49409c77815885bfe7ca5863a5382cb616e3500f
diff --git a/Android.bp b/Android.bp
index 090d91c..410b1de 100644
--- a/Android.bp
+++ b/Android.bp
@@ -2,6 +2,7 @@
     name: "libtinyalsa",
     host_supported: true,
     vendor_available: true,
+    product_available: true,
     vndk: {
         enabled: true,
     },