umount.c in the mount-2.9u-4.src.rpm package complains with the following
when compiled without the -DHAVE_NFS define:

gcc -c -Wall -Wstrict-prototypes -Wmissing-prototypes -I./lib   umount.c
umount.c: In function `umount_one':
umount.c:235: warning: implicit declaration of function `perror'
umount.c:238: warning: implicit declaration of function `printf'
umount.c:267: warning: implicit declaration of function `fprintf'
umount.c:267: `stderr' undeclared (first use in this function)
umount.c:267: (Each undeclared identifier is reported only once
umount.c:267: for each function it appears in.)
umount.c: In function `main':
umount.c:419: `EOF' undeclared (first use in this function)
umount.c:428: `stdout' undeclared (first use in this function)
umount.c:449: `stderr' undeclared (first use in this function)
make: *** [umount.o] Error 1

If you leave DEFINES=-DHAVE_NFS in the spec file, everything is
fine.