an fpos_t, use ftell which returns an int. Without the patch,
Bochs gets an fpos_t and assumes it is an integer type, but
on some systems (like linux with newer glibc libraries) this
assumption is wrong. Malte Cornils <malte@cornils.net> first
reported this bug, and he warned me that ftell may not be portable
to some platforms which treat binary and ascii streams differently.
I haven't found any alternative yet.