Fix build of tests with libc++

- libc++, like the MSVC STL, rejects char types in
  std::uniform_int_distribution.
- Skip the std::complex<long double> reference tests: with libc++ they do
  not compile for the device side.
--- a/test/test_complex_various.cpp
+++ b/test/test_complex_various.cpp
@@ -703,6 +703,10 @@ TYPED_TEST(VariousComplexTest, catan)
     1000);
 }
 
+// clang's cuda_wrappers/complex makes the libc++ std::complex functions
+// __host__ __device__; for long double they call std::isinf() etc., which
+// have no device overloads
+#ifndef _LIBCPP_VERSION
 TEST(VariousComplexTest, acos_long_double)
 {
   run_trig_tests<long double>(
@@ -792,6 +796,7 @@ TEST(VariousComplexTest, atanh_long_double)
     0,
     1);
 }
+#endif
 
 // ===================================================================
 //
--- a/test/test_utils.hpp
+++ b/test/test_utils.hpp
@@ -389,7 +389,7 @@ inline auto get_random_data(size_t size, T, T, seed_type seed) ->
   return data;
 }
 
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) || defined(_LIBCPP_VERSION)
 template <class T>
 inline auto get_random_data(size_t size, T min, T max, seed_type seed) ->
   typename std::enable_if_t<std::is_same_v<T, signed char> || (std::is_same_v<T, char> && std::is_signed_v<char>),
@@ -426,7 +426,7 @@ inline auto get_random_data(size_t size, T min, T max, seed_type seed) ->
 template <class T>
 inline auto get_random_data(size_t size, T min, T max, seed_type seed) -> typename std::enable_if_t<
   rocprim::is_integral<T>::value && !std::is_same_v<T, bool>
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) || defined(_LIBCPP_VERSION)
     && !std::is_same_v<T, signed char> && !std::is_same_v<T, unsigned char> && !std::is_same_v<T, char>
 #endif
   ,