pptsetup: Do not mess up the password when reading from stdin#1

Not sure whether this is the correct place to suggest patches, but the mailing list seems to be dead nowadays and here I see some commits newer than then newest post there so ;] Before this patch the trailing newline, which Perl by default leaves, had been included in the resulting configuration, thus having absolutely no chance to work without passing it via `--password`, which is *super insecure* due to being stored in shell's history and, quite often, showing up again in surprising ways.