util.c: use log_failure in check_access_flags
remove ncrctk from build system
command_tag.c: dirty-fix SIGSEV due to off-by-one assignment

Valgrind report:

  ==18343== Invalid write of size 1
  ==18343==    at 0x402E21: command_tag (command_tag.c:109)
  ==18343==    by 0x401BA0: main (crctk.c:180)
  ==18343==  Address 0x678d9e8 is 0 bytes after a block of size 72 alloc'd
  ==18343==    at 0x4C28C20: malloc (in
  /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
  ==18343==    by 0x402CCD: command_tag (command_tag.c:76)
  ==18343==    by 0x401BA0: main (crctk.c:180)

TODO:

  Investigate why this bug surfaced; this code has been unchanged for
  months...