Renames interface field in VpxInterface

Renames interface to codec_interface since it is a reserved
word on windows.

Change-Id: I84f2cbf257a4c44f16dc2464127e35ee405c2c3e
diff --git a/examples/simple_decoder.c b/examples/simple_decoder.c
index 8c15051..3318758 100644
--- a/examples/simple_decoder.c
+++ b/examples/simple_decoder.c
@@ -123,9 +123,9 @@
   if (!decoder)
     die("Unknown input codec.");
 
-  printf("Using %s\n", vpx_codec_iface_name(decoder->interface()));
+  printf("Using %s\n", vpx_codec_iface_name(decoder->codec_interface()));
 
-  if (vpx_codec_dec_init(&codec, decoder->interface(), NULL, 0))
+  if (vpx_codec_dec_init(&codec, decoder->codec_interface(), NULL, 0))
     die_codec(&codec, "Failed to initialize decoder.");
 
   while (vpx_video_reader_read_frame(reader)) {