don't forward declare enums

doing so is not part of ISO C; removes some pedantic warnings

Change-Id: I739ad8c5cacc133e2546e9f45c0db9d92fb93d7e

src/webp/mux.h

@@ -53,26 +53,26 @@ extern "C" {
 
 #define WEBP_MUX_ABI_VERSION 0x0100        // MAJOR(8b) + MINOR(8b)
 
+// Note: forward declaring enumerations is not allowed in (strict) C and C++,
+// the types are left here for reference.
+// typedef enum WebPMuxError WebPMuxError;
+// typedef enum WebPChunkId WebPChunkId;
 typedef struct WebPMux WebPMux;   // main opaque object.
-#if !(defined(__cplusplus) || defined(c_plusplus))
-typedef enum WebPMuxError WebPMuxError;
-typedef enum WebPChunkId WebPChunkId;
-#endif
 typedef struct WebPMuxFrameInfo WebPMuxFrameInfo;
 typedef struct WebPMuxAnimParams WebPMuxAnimParams;
 
 // Error codes
-enum WebPMuxError {
+typedef enum WebPMuxError {
   WEBP_MUX_OK                 =  1,
   WEBP_MUX_NOT_FOUND          =  0,
   WEBP_MUX_INVALID_ARGUMENT   = -1,
   WEBP_MUX_BAD_DATA           = -2,
   WEBP_MUX_MEMORY_ERROR       = -3,
   WEBP_MUX_NOT_ENOUGH_DATA    = -4
-};
+} WebPMuxError;
 
 // IDs for different types of chunks.
-enum WebPChunkId {
+typedef enum WebPChunkId {
   WEBP_CHUNK_VP8X,     // VP8X
   WEBP_CHUNK_ICCP,     // ICCP
   WEBP_CHUNK_ANIM,     // ANIM
@@ -84,7 +84,7 @@ enum WebPChunkId {
   WEBP_CHUNK_XMP,      // XMP
   WEBP_CHUNK_UNKNOWN,  // Other chunks.
   WEBP_CHUNK_NIL
-};
+} WebPChunkId;
 
 //------------------------------------------------------------------------------