Fix UnpackBits (#4227)

In UnpackBits I re-filled the buffer even if the amount of bits in the buffer was equal to the number of bits read. As a result, when the last value was read and the buffer was empty, I would still re-fill it, causing an out-of-bounds read.

Signed-off-by: Szymon Karpiński <skarpinski@nvidia.com>

dali/imgcodec/decoders/libtiff/tiff_libtiff.cc

@@ -196,7 +196,7 @@ void DLL_PUBLIC UnpackBits(size_t nbits, OutputType *out, const void *in, size_t
     OutputType result = 0;
     size_t bits_to_read = nbits;
     while (bits_to_read > 0) {
-      if (bits_in_buffer > bits_to_read) {
+      if (bits_in_buffer >= bits_to_read) {
         // If we have enough bits in the buffer, we store them and finish
         result <<= bits_to_read;
         result |= buffer >> (buffer_capacity - bits_to_read);