64 bit LFS compile error

["Leslie Rhorer" <lrhorer@satx.rr.com>]

I downloaded an application (mfs-tools) which I am trying to compile on my
Debian "Lenny" system, but the make is failing with the following errors:

gcc -DHAVE_CONFIG_H -I. -I../include -I../include    -g -O2 -MT
readwrite.o -MD -MP -MF .deps/readwrite.Tpo -c -o readwrite.o readwrite.c
readwrite.c: In function 'tivo_partition_read':
readwrite.c:146: error: 'off64_t' undeclared (first use in this function)
readwrite.c:146: error: (Each undeclared identifier is reported only once
readwrite.c:146: error: for each function it appears in.)
readwrite.c:146: error: expected ')' before 'sector'
readwrite.c:146: error: expected ')' before 'sector'
readwrite.c: In function 'tivo_partition_write':
readwrite.c:261: error: 'off64_t' undeclared (first use in this function)
readwrite.c:261: error: expected ')' before 'sector'
readwrite.c:261: error: expected ')' before 'sector'
make[1]: *** [readwrite.o] Error 1
make[1]: Leaving directory `/downloads/software/mfstools-src/lib'
make: *** [all-recursive] Error 1

I've searched for the error, and I found some background information, but no
clear suggestions on how to resolve the issue.  I submitted the issue to
some Usenet groups, and one of the respondents suggested I report the issue
here.  Clearly, the off64_t type is not defined in any of the headers.  I
have glibc-source installed, and it looks to me like the type may be
defined there, but the make is not seeing it.