metadata: do not emit broken kconfig dependency statements

Prevent emitting broken dependency statements when resolving references
to non existing packages to an empty provider list.

Fixes: 47d6b05ad3 ("metadata: always resolve dependencies through provides list")
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

scripts/package-metadata.pl

@@ -209,7 +209,7 @@ sub mconf_depends {
 			$flags =~ /@/ or $depend = "PACKAGE_$depend";
 		} else {
 			my $vdep = $vpackage{$depend};
-			if ($vdep) {
+			if ($vdep && @$vdep > 0) {
 				$depend = join("||", map { "PACKAGE_".$_->{name} } @$vdep);
 			} else {
 				$flags =~ /@/ or $depend = "PACKAGE_$depend";