scripts/*.sh.in: Honor TMPDIR environment variable

Replace "/tmp" with "${TMPDIR:-/tmp}" to allow for overriding the
hardcoded path.

Since we only use "/tmp" in conjunction with mktemp(1), we could also
have used "--tmpdir", which is GNU-ish, however (and the BSD counterpart
"-t" has been deprecated in GNU mktemp).

Signed-off-by: Lukas Fleischer <archlinux@cryptocrack.de>
Signed-off-by: Dan McGee <dan@archlinux.org>

scripts/pacman-optimize.sh.in

@@ -113,7 +113,7 @@ fi
 # do not let pacman run while we do this
 touch "$lockfile"
 
-workdir=$(mktemp -d /tmp/pacman-optimize.XXXXXXXXXX) ||
+workdir=$(mktemp -d "${TMPDIR:-/tmp}/pacman-optimize.XXXXXXXXXX") ||
 	die_r "$(gettext "Can not create temp directory for database building.")\n" >&2
 
 # step 1: sum the old db

scripts/repo-add.sh.in

@@ -560,7 +560,7 @@ if [[ $cmd != "repo-add" && $cmd != "repo-remove" ]]; then
 	exit 1
 fi
 
-tmpdir=$(mktemp -d /tmp/repo-tools.XXXXXXXXXX) || (\
+tmpdir=$(mktemp -d "${TMPDIR:-/tmp}/repo-tools.XXXXXXXXXX") || (\
 	error "$(gettext "Cannot create temp directory for database building.")"; \
 	exit 1)
 mkdir $tmpdir/tree