dpkg: Remove path_quote_filename() usage

The original problem for which this function was introduced in
commit 520ad305, is no longer relevant
since commit 1a8d1228 where the varbuf
function doing vprintf was fixed to not loop infinitely. Changes in
commit 520ad305, further changed the
code to not even pass the filenames to fd_fd_copy() anymore, and instead
call the ohshit() functions from the call sites.

We leave the function around for now, if this ends up not being useful
for anything it will be eventually removed.

Warned-by: cppcheck
Changelog: internal