Simplify aomenc API - remove AvxInterface

AvxInterface adds extra indirection between user code and
aom_codec_iface_t, the interface data structure. Instead of
exposing it, hide it from the interface and return
aom_codec_iface_t directly.

Also explicitly differentiate "codec short name" (e.g., "av1") from
"codec name" (e.g., "AOMedia Project AV1 Encoder
1.0.0-errata1-avif-714-g15e1944a5")

BUG=aomedia:2651

Change-Id: Iba114972d954a2457055e97f174520a0119ace41

examples/inspect.c

diff --git a/examples/inspect.c b/examples/inspect.c
index 526bdc1..27171f4 100644
--- a/examples/inspect.c
+++ b/examples/inspect.c
@@ -755,11 +755,10 @@
   reader = aom_video_reader_open(file);
   if (!reader) die("Failed to open %s for reading.", file);
   info = aom_video_reader_get_info(reader);
-  const AvxInterface *decoder = get_aom_decoder_by_fourcc(info->codec_fourcc);
+  aom_codec_iface_t *decoder = get_aom_decoder_by_fourcc(info->codec_fourcc);
   if (!decoder) die("Unknown input codec.");
-  fprintf(stderr, "Using %s\n",
-          aom_codec_iface_name(decoder->codec_interface()));
-  if (aom_codec_dec_init(&codec, decoder->codec_interface(), NULL, 0))
+  fprintf(stderr, "Using %s\n", aom_codec_iface_name(decoder));
+  if (aom_codec_dec_init(&codec, decoder, NULL, 0))
     die_codec(&codec, "Failed to initialize decoder.");
   ifd_init(&frame_data, info->frame_width, info->frame_height);
   ifd_init_cb();