Convert libaaudio to Android.bp

See build/soong/README.md for more information about Soong.

I didn't translate the examples, since they appear to be NDK build
files, not platform build files.

Test: mmma frameworks/av/media/libaaudio
Change-Id: Icf228c701afe37dd3c7f00ea9e6fb740b0d450f1
Merged-In: Icf228c701afe37dd3c7f00ea9e6fb740b0d450f1
diff --git a/media/libaaudio/Android.bp b/media/libaaudio/Android.bp
index 6e60f24..f00f7a8 100644
--- a/media/libaaudio/Android.bp
+++ b/media/libaaudio/Android.bp
@@ -28,3 +28,10 @@
     first_version: "26",
     unversioned_until: "current",
 }
+
+cc_library_headers {
+    name: "libaaudio_headers",
+    export_include_dirs: ["include"],
+}
+
+subdirs = ["*"]