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: I28134bdb1834ac582645474747e5ab28166ec169
diff --git a/Android.bp b/Android.bp
index 290835f..e297beb 100644
--- a/Android.bp
+++ b/Android.bp
@@ -18,6 +18,7 @@
     name: "libspeexresampler",
 
     vendor_available: true,
+    product_available: true,
     vndk: {
         enabled: true,
     },