Apply version script to libamidi.so

Hide unintentionally exported symbols, validate that symbols
mentioned in the map file are actually exported by the library.

Bug: http://b/69603741
Test: make
Change-Id: I53deafa7d730944eaccc044be44f535c720a2985
diff --git a/media/native/midi/Android.bp b/media/native/midi/Android.bp
index 58317ed..a0d20506 100644
--- a/media/native/midi/Android.bp
+++ b/media/native/midi/Android.bp
@@ -40,6 +40,8 @@
         "libandroid_runtime",
     ],
 
+    version_script: "libamidi.map.txt",
+
     export_include_dirs: ["include"],
 }