vpx/vpx_encoder.h: bump ABI version

missed in updates for high bitdepth, others

Change-Id: Id30076ce09beb361b5e1ff0ac99e3ae1ad4f987e

vpx/vpx_encoder.h

diff --git a/vpx/vpx_encoder.h b/vpx/vpx_encoder.h
index 8977ec4..2522235 100644
--- a/vpx/vpx_encoder.h
+++ b/vpx/vpx_encoder.h
@@ -59,7 +59,7 @@
    * types, removing or reassigning enums, adding/removing/rearranging
    * fields to structures
    */
-#define VPX_ENCODER_ABI_VERSION (3 + VPX_CODEC_ABI_VERSION) /**<\hideinitializer*/
+#define VPX_ENCODER_ABI_VERSION (4 + VPX_CODEC_ABI_VERSION) /**<\hideinitializer*/
 
 
   /*! \brief Encoder capabilities bitfield