Only include webm headers in libmediaplayerservice

Binary included both static + shared copies of same library. This caused static
constructors/destructors to run twice, causing pointer/free havoc.

Bug: 227660073
Test: boot
Test: atest android.media.player.cts.MediaPlayerTest
Change-Id: Ib9790771375e1cab39d0e76ee48b893b435ae27a