[Fix] Possible out-of-bounds read when computing length of some IT files with pattern loops (OpenMPT: formats that are converted to IT, libopenmpt: IT/ITP/MO3), caught with afl-fuzz.

git-svn-id: https://source.openmpt.org/svn/openmpt/trunk/OpenMPT@10027 56274372-70c3-4bfc-bfc3-4c3a0b034d27
void CSoundFile::Panbrello(ModChannel *p, uint32 param) const
{
	if (param & 0x0F) p->nPanbrelloDepth = param & 0x0F;
	if (param & 0xF0) p->nPanbrelloSpeed = (param >> 4) & 0x0F;
}

void CSoundFile::Panbrello(ModChannel *p, uint32 param) const
{
	if (param & 0x0F) p->nPanbrelloDepth = param & 0x0F;
	if (param & 0xF0) p->nPanbrelloSpeed = (param >> 4) & 0x0F;
}
