Mk/Scripts: Fix ports depends-list.sh

depends-list.sh fails in two ways: one is a simple quoting bug which
causes empty FLAVOR variables to be propagated; the other is that
de-duplication is being done without regard for flavors.

The upshot of these is that where a port depends on a specific flavor
(first bug) or on multiple flavors (second bug, usually caused by build
dependencies) of another port, the constructed dependency list is
incomplete, and so -recursive targets do not do all the required work.
(This is especially annoying for fetch-recursive.)

Reviewed by: portmgr@FreeBSD.org
PR:		269982
Differential Revision: https://reviews.freebsd.org/D40491

Mk/Scripts/depends-list.sh

@@ -76,7 +76,7 @@ check_dep() {
 				;;
 			esac
 			if [ -f ${d}/Makefile ]; then
-				if [ -n $f ]; then
+				if [ -n "$f" ]; then
 					export FLAVOR=$f
 				fi
 				break
@@ -91,9 +91,9 @@ check_dep() {
 		fi
 
 		case " ${checked} " in
-			*\ ${d}\ *) continue ;; # Already checked
+			*\ ${port_display}\ *) continue ;; # Already checked
 		esac
-		checked="${checked} ${d}"
+		checked="${checked} ${port_display}"
 		# Check if the dependency actually exists or skip otherwise.
 		if [ ! -d "${d}" ]; then
 			echo "${dp_PKGNAME}: \"${port_display}\" non-existent -- dependency list incomplete" >&2