Revert "Audio V4: Split system and vendor Audio.h"

This reverts commit fc9e212f018ce41430ec8dcebc3cae3c346474bb.

Reason for revert: Breaks multiple devices

Change-Id: I816671fd92246f85c97d00819858a74e36e2929d
diff --git a/Android.bp b/Android.bp
index fd138b0..4766b71 100644
--- a/Android.bp
+++ b/Android.bp
@@ -3,11 +3,13 @@
 cc_library_headers {
     name: "libhardware_headers",
     header_libs: [
+        "libaudio_system_headers",
         "libsystem_headers",
         "libcutils_headers",
         "libbluetooth-types-header",
     ],
     export_header_lib_headers: [
+        "libaudio_system_headers",
         "libsystem_headers",
         "libcutils_headers",
         "libbluetooth-types-header",