bulk copy of latest physfs to our misc/libphysfs since this seems to fix an off-by-1 error reliably hit in readln read of 1 byte probably introduced in the addition of the buffered read. Whether this is excessive or whether libphysfs should even be maintained by us is another matter. But at least we shouldn't crash

/*  7zHeader.c */

#include "7zHeader.h"

Byte k7zSignature[k7zSignatureSize] = {'7', 'z', 0xBC, 0xAF, 0x27, 0x1C};