mark VP8{,L}{GetInfo,CheckSignature} as WEBP_EXTERN

these functions are used by libwebpmux

Change-Id: Ifcb79e685f3a6b53007c0dc5f220737daba97d47

src/dec/vp8.c

@@ -94,7 +94,7 @@ int VP8CheckSignature(const uint8_t* const data, size_t data_size) {
 }
 
 int VP8GetInfo(const uint8_t* data, size_t data_size, size_t chunk_size,
-               int* width, int* height) {
+               int* const width, int* const height) {
   if (data == NULL || data_size < VP8_FRAME_HEADER_SIZE) {
     return 0;         // not enough data
   }

src/dec/vp8i.h

@@ -290,17 +290,6 @@ struct VP8Decoder {
 int VP8SetError(VP8Decoder* const dec,
                 VP8StatusCode error, const char* const msg);
 
-// Returns true if the next 3 bytes in data contain the VP8 signature.
-int VP8CheckSignature(const uint8_t* const data, size_t data_size);
-
-// Validates the VP8 data-header and retrieves basic header information viz
-// width and height. Returns 0 in case of formatting error. *width/*height
-// can be passed NULL.
-int VP8GetInfo(const uint8_t* data,
-               size_t data_size,    // data available so far
-               size_t chunk_size,   // total data size expect in the chunk
-               int *width, int *height);
-
 // in tree.c
 void VP8ResetProba(VP8Proba* const proba);
 void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec);

src/dec/vp8li.h

@@ -87,15 +87,6 @@ typedef struct {
 
 // in vp8l.c
 
-// Returns true if the next byte(s) in data is a VP8L signature.
-int VP8LCheckSignature(const uint8_t* const data, size_t size);
-
-// Validates the VP8L data-header and retrieves basic header information viz
-// width, height and alpha. Returns 0 in case of formatting error.
-// width/height/has_alpha can be passed NULL.
-int VP8LGetInfo(const uint8_t* data, size_t data_size,  // data available so far
-                int* const width, int* const height, int* const has_alpha);
-
 // Decodes a raw image stream (without header) and store the alpha data
 // into *output, which must be of size width x height. Returns false in case
 // of error.

src/webp/decode_vp8.h

@@ -151,6 +151,29 @@ WEBP_EXTERN(void) VP8Clear(VP8Decoder* const dec);
 WEBP_EXTERN(void) VP8Delete(VP8Decoder* const dec);
 
 //------------------------------------------------------------------------------
+// Miscellaneous VP8/VP8L bitstream probing functions.
+
+// Returns true if the next 3 bytes in data contain the VP8 signature.
+WEBP_EXTERN(int) VP8CheckSignature(const uint8_t* const data, size_t data_size);
+
+// Validates the VP8 data-header and retrieves basic header information viz
+// width and height. Returns 0 in case of formatting error. *width/*height
+// can be passed NULL.
+WEBP_EXTERN(int) VP8GetInfo(
+    const uint8_t* data,
+    size_t data_size,    // data available so far
+    size_t chunk_size,   // total data size expected in the chunk
+    int* const width, int* const height);
+
+// Returns true if the next byte(s) in data is a VP8L signature.
+WEBP_EXTERN(int) VP8LCheckSignature(const uint8_t* const data, size_t size);
+
+// Validates the VP8L data-header and retrieves basic header information viz
+// width, height and alpha. Returns 0 in case of formatting error.
+// width/height/has_alpha can be passed NULL.
+WEBP_EXTERN(int) VP8LGetInfo(
+    const uint8_t* data, size_t data_size,  // data available so far
+    int* const width, int* const height, int* const has_alpha);
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }    // extern "C"