lavc/vvc: Reallocate pixel buffers if pixel shift changes

Allocations in the following lines depend on the pixel shift, and so
these buffers must be reallocated if the pixel shift changes.  Patch
fixes segmentation faults in fuzzed bitstreams.

Signed-off-by: Frank Plowman <post@frankplowman.com>

libavcodec/vvc/dec.c

@@ -214,7 +214,8 @@ static void pixel_buffer_nz_tl_init(TabList *l, VVCFrameContext *fc)
     const int c_end      = chroma_idc ? VVC_MAX_SAMPLE_ARRAYS : 1;
     const int changed    = fc->tab.sz.chroma_format_idc != chroma_idc ||
         fc->tab.sz.width != width || fc->tab.sz.height != height ||
-        fc->tab.sz.ctu_width != ctu_width || fc->tab.sz.ctu_height != ctu_height;
+        fc->tab.sz.ctu_width != ctu_width || fc->tab.sz.ctu_height != ctu_height ||
+        fc->tab.sz.pixel_shift != ps;
 
     tl_init(l, 0, changed);