example_util.h: avoid forward declaring enums

doing so is not part of ISO C; removes some pedantic warnings.
use webp/decode.h to pickup VP8StatusCode instead.

Change-Id: I19b35e0f8a36fb7c45944ae9ca86838e08b90548
diff --git a/examples/example_util.h b/examples/example_util.h
index 8a9f68b..bf90c35 100644
--- a/examples/example_util.h
+++ b/examples/example_util.h
@@ -13,15 +13,12 @@
 #ifndef WEBP_EXAMPLES_EXAMPLE_UTIL_H_
 #define WEBP_EXAMPLES_EXAMPLE_UTIL_H_
 
-#include "webp/types.h"
+#include "webp/decode.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-struct WebPDecoderConfig;
-struct WebPBitstreamFeatures;
-
 // Allocates storage for entire file 'file_name' and returns contents and size
 // in 'data' and 'data_size'. Returns 1 on success, 0 otherwise. '*data' should
 // be deleted using free().
@@ -51,7 +48,7 @@
 // Returns true on success.
 int ExUtilLoadWebP(const char* const in_file,
                    const uint8_t** data, size_t* data_size,
-                   struct WebPBitstreamFeatures* bitstream);
+                   WebPBitstreamFeatures* bitstream);
 
 // Decodes the WebP contained in 'data'.
 // 'config' is a structure previously initialized by WebPInitDecoderConfig().
@@ -59,14 +56,13 @@
 // cause decode timing to be reported.
 // Returns the decoder status. On success 'config->output' will contain the
 // decoded picture.
-enum VP8StatusCode ExUtilDecodeWebP(const uint8_t* const data, size_t data_size,
-                                    int verbose,
-                                    struct WebPDecoderConfig* const config);
+VP8StatusCode ExUtilDecodeWebP(const uint8_t* const data, size_t data_size,
+                               int verbose, WebPDecoderConfig* const config);
 
 // Same as ExUtilDecodeWebP(), but using the incremental decoder.
-enum VP8StatusCode ExUtilDecodeWebPIncremental(
+VP8StatusCode ExUtilDecodeWebPIncremental(
     const uint8_t* const data, size_t data_size,
-    int verbose, struct WebPDecoderConfig* const config);
+    int verbose, WebPDecoderConfig* const config);
 
 #ifdef __cplusplus
 }    // extern "C"