src/platform/openbsd.sh: remove tmpdir (#27)

OpenBSD has removed the platform specific tmpdir() definition for OpenBSD from their port of password-store since 2017.
Reference: 
openbsd/ports@dfc0e73
https://cvsweb.openbsd.org/ports/security/password-store/patches/patch-src_platform_openbsd_sh?rev=1.1&content-type=text/x-cvsweb-markup

Author: VlkrS

src/platform/openbsd.sh

@@ -2,40 +2,6 @@
 # Copyright (C) 2015 David Dahlberg <david.dahlberg@fkie.fraunhofer.de>. All Rights Reserved.
 # This file is licensed under the GPLv2+. Please see COPYING for more information.
 
-tmpdir() {
-	[[ -n $SECURE_TMPDIR ]] && return
-	local warn=1
-	[[ $1 == "nowarn" ]] && warn=0
-	local template="$PROGRAM.XXXXXXXXXXXXX"
-	if [[ $(sysctl -n kern.usermount) == 1 ]]; then
-		SECURE_TMPDIR="$(mktemp -d "${TMPDIR:-/tmp}/$template")"
-		mount -t tmpfs -o -s16M tmpfs "$SECURE_TMPDIR" || die "Error: could not create tmpfs."
-		unmount_tmpdir() {
-			 [[ -n $SECURE_TMPDIR && -d $SECURE_TMPDIR ]] || return
-			 umount "$SECURE_TMPDIR"
-			 rm -rf "$SECURE_TMPDIR"
-		}
-		trap unmount_tmpdir INT TERM EXIT
-	else
-		[[ $warn -eq 1 ]] && yesno "$(cat <<-_EOF
-		The sysctl kern.usermount is disabled, therefore it is not
-		possible to create a tmpfs for temporary storage of files
-		in memory.
-		This means that it may be difficult to entirely erase
-		the temporary non-encrypted password file after editing.
-
-		Are you sure you would like to continue?
-		_EOF
-		)"
-		SECURE_TMPDIR="$(mktemp -d "${TMPDIR:-/tmp}/$template")"
-		shred_tmpfile() {
-			find "$SECURE_TMPDIR" -type f -exec $SHRED {} +
-			rm -rf "$SECURE_TMPDIR"
-		}
-		trap shred_tmpfile INT TERM EXIT
-	fi
-}
-
 GETOPT="gnugetopt"
 SHRED="rm -P -f"
 BASE64="openssl base64"