gpujpeg_dct_cpu: allocate CPU quant data buf

Since the commit 41fb824 (2025-01-25), the buffer is no longer allocated
automatically but is used by this piece of code.

CPU iDCT is never used, however (but could be used instead of GPU
implemetation as indicated by added commented-out code).

Author: MartinPulec

src/gpujpeg_dct_cpu.c

@@ -206,6 +206,11 @@ gpujpeg_idct_cpu(struct gpujpeg_decoder* decoder)
 
     // Get coder
     struct gpujpeg_coder* coder = &decoder->coder;
+    if ( coder->data_quantized == NULL ) {
+        if ( gpujpeg_coder_allocate_cpu_huffman_buf(coder) != 0 ) {
+            abort();
+        }
+    }
 
     // Perform IDCT and dequantization
     for ( int comp = 0; comp < coder->param.comp_count; comp++ ) {

src/gpujpeg_decoder.c

@@ -325,6 +325,7 @@ gpujpeg_decoder_decode(struct gpujpeg_decoder* decoder, uint8_t* image, size_t i
     if (0 != gpujpeg_idct_gpu(decoder)) {
         return -1;
     }
+    // gpujpeg_idct_cpu(decoder);
 
     GPUJPEG_CUSTOM_TIMER_STOP(coder->duration_dct_quantization, coder->param.perf_stats, decoder->stream, return -1);