Fix uninitialized read in decompress_smooth_data() Regression introduced by 42825b68d570fb07fe820ac62ad91017e61e9a25 Referring to the discussion in #459, the OSS-Fuzz test case https://github.com/libjpeg-turbo/libjpeg-turbo/files/5597075/clusterfuzz-testcase-minimized-pngsave_buffer_fuzzer-5728375846731776.txt created a situation in which cinfo->output_iMCU_row > cinfo->master->last_good_iMCU_row but cinfo->input_scan_number == 1 thus causing decompress_smooth_data() to read from prev_coef_bits_latch[], which was uninitialized. I was unable to create the same situation with a real JPEG image.