[osx] Fix number of bits used per channel/sample on 32-bit RGB images…

… (without alpha)

Fix aseprite/aseprite#4102

clip_osx.mm

@@ -56,7 +56,10 @@ bool get_image_from_clipboard(image* output_img,
 
     // We need three samples for Red/Green/Blue
     if (bitmap.samplesPerPixel >= 3) {
-      int bits_per_sample = bitmap.bitsPerPixel / bitmap.samplesPerPixel;
+      // Here we are guessing the bits per sample (generally 8, not
+      // sure how many bits per sample macOS uses for 16bpp
+      // NSBitmapFormat or if this format is even used).
+      int bits_per_sample = (bitmap.bitsPerPixel == 16 ? 5: 8);
       int bits_shift = 0;
 
       // With alpha