bashrc: Remove overriding of dirs Bash builtin

The lesson is to RTFM.  I just read in builtins(7):

    dirs [+n] [-n] [-cplv]
    ...
    -v     Print the directory stack with one entry per  line,  pre‐
           fixing each entry with its index in the stack.

...so 'dirs -v' will do what I had accomplished with the Perl one-liner.