kldxref: Add -m filag to print info about modules in one file

[imp]

Summary

kldxref -m <file> will print the same data that the '-d' flag produces,
except restrict the output to one file. This should be the full path to
the file, and the directory name to process is omitted.

Sponsored by: Netflix

[jrtc27]

usr.sbin/kldxref/kldxref.c

796

Isn't < 0 impossible, as that would imply getopt ran off the end of argv? And don't you want to check that no extra arguments were passed for -m, given we skip the fts_open(argv)? That is:

if ((module != NULL && argc - optind > 0) || (module == NULL && argc - optind < 1))

or, if you want to be sneaky:

if ((module == NULL) == (argc - optind < 1))