Suppress implicit-fallthrough warnings in mpeg2.

Add FALLTHROUGH_INTENDED for clang compiler.

Bug: 112564944
Test: build with global -Wimplicit-fallthrough.
Change-Id: Ibf9aa0c2bf6ca13dbe96662061cb26b66e9e10d6
diff --git a/media/extractors/mpeg2/Android.bp b/media/extractors/mpeg2/Android.bp
index 5e4a592..40314dc 100644
--- a/media/extractors/mpeg2/Android.bp
+++ b/media/extractors/mpeg2/Android.bp
@@ -25,6 +25,10 @@
         "libstagefright_foundation",
     ],
 
+    header_libs: [
+        "libbase_headers",
+    ],
+
     static_libs: [
         "libstagefright_mpeg2support",
         "libutils",