makepkg: more bash-3.2 compatibility

Adding the "|| true" to the subshell prevents bash-3.2 setting off the
error_trap but requires changing the if statement.

Signed-off-by: Allan McRae <allan@archlinux.org>
Signed-off-by: Dan McGee <dan@archlinux.org>

scripts/makepkg.sh.in

@@ -507,8 +507,8 @@ download_sources() {
 
 	local netfile
 	for netfile in "${source[@]}"; do
-		local file
-		if file=$(get_filepath "$netfile"); then
+		local file=$(get_filepath "$netfile" || true)
+		if [[ -n "$file" ]]; then
 			msg2 "$(gettext "Found %s")" "${file##*/}"
 			ln -sf "$file" "$srcdir/"
 			continue