* path.cc (cygdrive_getmntent): Do not skip over drives of type

* path.cc (cygdrive_getmntent): Do not skip over drives of type
DRIVE_REMOVABLE.
* fhandler.cc (fhandler_base::lseek): Be more paranoid when constructing
offsets from 64 bit value.
* syscalls.cc (logout): Avoid temp buffer memcpy since new scheme does not
require it.
(utmp_data): Rework as a macro which returns a pointer into a buffer.
(getutent): Use new buffer allocation mechanism to grab a utmp buffer.
(getutid): Ditto.
(pututline): Ditto.