abstract apply_temporal_filter

allow for optimized versions of apply_temporal_filter
(now vp8_apply_temporal_filter_c)

the function was previously declared as static and appears to have been
inlined. with this change, that's no longer possible. performance takes
a small hit.

the declaration for vp8_cx_temp_filter_c was moved to onyx_if.c because
of a circular dependency. for rtcd, temporal_filter.h holds the
definition for the rtcd table, so it needs to be included by onyx_int.h.
however, onyx_int.h holds the definition for VP8_COMP which is needed
for the function prototype. blah.

Change-Id: I499c055fdc652ac4659c21c5a55fe10ceb7e95e3
diff --git a/vp8/encoder/onyx_int.h b/vp8/encoder/onyx_int.h
index 56938be..990ae1d 100644
--- a/vp8/encoder/onyx_int.h
+++ b/vp8/encoder/onyx_int.h
@@ -27,6 +27,7 @@
 #include "vpx_ports/mem.h"
 #include "vpx/internal/vpx_codec_internal.h"
 #include "mcomp.h"
+#include "temporal_filter.h"
 
 //#define SPEEDSTATS 1
 #define MIN_GF_INTERVAL             4
@@ -228,6 +229,7 @@
     vp8_encodemb_rtcd_vtable_t  encodemb;
     vp8_quantize_rtcd_vtable_t  quantize;
     vp8_search_rtcd_vtable_t    search;
+    vp8_temporal_rtcd_vtable_t  temporal;
 } VP8_ENCODER_RTCD;
 
 enum