makepkg: fix a GNU-ism in awk usage

A non-GNU version of awk may not support the (|...) syntax for
an optional group and require '()' to match an empty string.
The (...)? syntax is more appropriate for this usage.

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

scripts/makepkg.sh.in

@@ -1275,7 +1275,7 @@ check_sanity() {
 	done
 
 	local optdepends_list=()
-	eval $(awk '/^[[:space:]]*optdepends=\(/,/\)[[:space:]]*(|#.*)$/' "$BUILDFILE" | \
+	eval $(awk '/^[[:space:]]*optdepends=\(/,/\)[[:space:]]*(#.*)?$/' "$BUILDFILE" | \
 		sed -e "s/optdepends=/optdepends_list+=/" -e "s/#.*//" -e 's/\\$//')
 	for i in "${optdepends_list[@]}"; do
 		local pkg=${i%%:*}