Fix test expectation to cope with custom version namespaces.

Author: zygoloid

libcxx/test/std/numerics/rand/rand.eng/rand.eng.lcong/params.fail.cpp

@@ -24,8 +24,8 @@ int main(int, char**)
     // expected-error@random:* {{static_assert failed due to requirement '1ULL == 0 || 1ULL < 1ULL' "linear_congruential_engine invalid parameters"}}
     std::linear_congruential_engine<T, 0, 1, 1> e3;
     std::linear_congruential_engine<T, 1, 0, 1> e4;
-    // expected-error@random:* {{static_assert failed due to requirement 'std::__1::is_unsigned<int>::value' "_UIntType must be unsigned type"}}
+    // expected-error-re@random:* {{static_assert failed due to requirement 'std:{{.*}}:is_unsigned<int>::value' "_UIntType must be unsigned type"}}
     std::linear_congruential_engine<int, 0, 0, 0> e5;
 
     return 0;
-}
+}