bug#63142: 30.0.50; QUOTING_STYLE can break dired

[Yuri D'Elia]

If the environment variable QUOTING_STYLE is set, GNU "ls" can return a
format that dired doesn't like.

QUOTING_STYLE=shell will quote files with spaces such as 'a b', and
trying to interact with these files with dired results in:

dired-get-file-for-visit: File no longer exists; type g to update Dired buffer

Interestingly, even using "ls --dired" does the same if QUOTING_STYLE is
set.

Should dired handle QUOTING_STYLE (looking at the coreutils manual it
seems that other tools besides ls handle it) or should dired actively
suppress the quoting mode?