makemacpkg.in: Allow universal DMG w/o ARMv8 arch

(buglet)
diff --git a/release/makemacpkg.in b/release/makemacpkg.in
index 42b455d..bbbfe6f 100644
--- a/release/makemacpkg.in
+++ b/release/makemacpkg.in
@@ -230,7 +230,7 @@
 	install_ios $BUILDDIRARMV7S ARMv7s armv7s arm
 fi
 
-if [ $UNIVERSAL = 1 -a "BUILDDIRARMV8" != "" ]; then
+if [ $UNIVERSAL = 1 -a "$BUILDDIRARMV8" != "" ]; then
 	install_ios $BUILDDIRARMV8 ARMv8 armv8 arm64
 fi