depmod: add tmpfile-util to generate temporary file

depmod: add tmpfile-util to generate temporary file

* we use `mkstemp` to create the temporary file since it's a general
  function in linux system and O_TMPFILE is not supported on all linux
  system.
* add `struct tmpfile` to keep the `dirfd`, temp file `fd` and the
  filename.

Co-developed-by: Wenjie Wang <wenjie2.wang@intel.com>
Signed-off-by: Wenjie Wang <wenjie2.wang@intel.com>
Co-developed-by: Gongjun Song <gongjun.song@intel.com>
Signed-off-by: Gongjun Song <gongjun.song@intel.com>
Signed-off-by: Dan He <dan.h.he@intel.com>
Signed-off-by: Qingqing Li <qingqing.li@intel.com>
Signed-off-by: Yuchi Chen <yuchi.chen@intel.com>
Link: https://github.com/kmod-project/kmod/pull/305
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>