fix universal test

tests/test/universal/DESCRIPTION

@@ -1,6 +1,6 @@
 This test checks the handling of the universal variant in MacPorts base.
 Every port should have an universal variant unless 'universal_variant no' is
-specified.
+specified, or there are less than two supported archs.
 
 There are 2 test cases. One for universal variant set and another for no
 universal variant. For each test a specific Portfile is generated from the

tests/test/universal/Portfile.in

@@ -15,4 +15,5 @@ destroot        {
         system "touch ${destroot}${prefix}/lib/${name}"
 }
 test            {}
+configure.universal_archs   i386 x86_64
 @option@