Remove use of ANSI-C Quoting for IFS

[dchanm]

IFS=$'\t\n'

That doesn't work as expected in POSIX shells because it is a BASH feature [1]. Variable quoting prevented the issue from manifesting. The fix is to use printf

IFS="$(printf '\t\n')"

echo has some implementation-defined behaviors [2]

[1] - https://www.gnu.org/software/bash/manual/html_node/ANSI_002dC-Quoting.html
[2] - http://pubs.opengroup.org/onlinepubs/009695399/utilities/echo.html