bash: disable `bash-malloc` everywhere, not just on `musl`

TIme to time I bump into pathological behaviour of `bash` memory
allocator. Today's example:

    $ time { ls /nix/store/ > /dev/null; }
    real    0m0,965s user    0m0,876s sys     0m0,087s
    $ time { echo /nix/store/* > /dev/null; }
    real    2m18,287s user    2m17,946s sys     0m0,125s
    $ time { echo /nix/store/* > /dev/null; }
    real    0m1,764s user    0m1,712s sys     0m0,048s

Note how initial `echo` takes alsmot 2 minutes to finish.

Let's rely  on system's allocator instead.

After the change initial run is fast again:

    $ time { echo /nix/store/* > /dev/null; }
    real    0m1,328s user    0m1,264s sys     0m0,063s

0 files changed, 0 insertions, 0 deletions