Use kvImageNoAllocate to avoid extra allocate for vImageBuffer when WebP encoding

Author: dreampiggy

SDWebImageWebPCoder/Classes/SDImageWebPCoder.m

@@ -782,7 +782,7 @@ - (nullable NSData *)sd_encodedWebpDataWithImage:(nullable CGImageRef)imageRef
         }
 
         vImage_Buffer src;
-        error = vImageBuffer_InitWithCGImage(&src, &srcFormat, nil, imageRef, kvImageNoFlags);
+        error = vImageBuffer_InitWithCGImage(&src, &srcFormat, nil, imageRef, kvImageNoAllocate);
         if (error != kvImageNoError) {
             vImageConverter_Release(convertor);
             return nil;
@@ -792,15 +792,13 @@ - (nullable NSData *)sd_encodedWebpDataWithImage:(nullable CGImageRef)imageRef
         error = vImageBuffer_Init(&dest, height, width, destFormat.bitsPerPixel, kvImageNoFlags);
         if (error != kvImageNoError) {
             vImageConverter_Release(convertor);
-            free(src.data);
             return nil;
         }
 
         // Convert input color mode to RGB888/RGBA8888
         error = vImageConvert_AnyToAny(convertor, &src, &dest, NULL, kvImageNoFlags);
 
         // Free the buffer
-        free(src.data);
         vImageConverter_Release(convertor);
         if (error != kvImageNoError) {
             free(dest.data);