Set min_sdk_version (for non-mainline files)

Modules contributing mainline modules (APK/APEX) should set
min_sdk_version as well as apex_available.

For now setting min_sdk_version doesn't change build outputs.
But build-time checks will be added soon.

This is second part of two CLs: covers non-mainline files

Bug: 152655956
Test: m
Change-Id: I55336e644990d3f175e0c011856b52ec600e452a
diff --git a/media/libaudiofoundation/Android.bp b/media/libaudiofoundation/Android.bp
index 93bc4d9..548b080 100644
--- a/media/libaudiofoundation/Android.bp
+++ b/media/libaudiofoundation/Android.bp
@@ -1,6 +1,8 @@
 cc_library_headers {
     name: "libaudiofoundation_headers",
     vendor_available: true,
+    min_sdk_version: "29",
+
     export_include_dirs: ["include"],
     header_libs: [
         "libaudio_system_headers",