ImageMagick: Heap overflow in pcd decoder leads to out of bounds read.

The pcd coder lacks proper boundary checking when processing Huffman-coded data. The decoder contains an function that has an incorrect initialization that could cause an out of bounds read. ==3900053==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x502000003c6c at pc 0x55601b9cc552 bp...