Completely revise dbskkd-cdb.c
Completely revise dbskkd-cdb.c

* Use `<sysexits.h>` exit code instead of `diesys()`
* Revise indentation and C code formatting with `clang-format`
* Remove `VERBOSE_MSG` flag

jj1bdx/dbskkd-cdb,jj1bdx/dbskkd-cdb