Fixes for multidevice/gcc.

- Allow devices to be cleared during benchmark definition.
- Fix various demangling bugs.

testing/benchmark.cu

@@ -222,6 +222,7 @@ void test_run()
   // More exhaustive testing is in runner.cu. This just tests that the
   // runner is called.
   no_types_bench bench;
+  bench.set_devices(std::vector<int>{});
   ASSERT(bench.get_states().empty());
   bench.run();
   ASSERT(bench.get_states().size() == 1);
@@ -230,6 +231,7 @@ void test_run()
 void test_clone()
 {
   lots_of_types_bench bench;
+  bench.set_devices(std::vector<int>{});
   bench.set_type_axes_names({"Integer", "Float", "Other"});
   bench.add_string_axis("Strings", {"string a", "string b", "string c"});
   bench.add_int64_power_of_two_axis("I64 POT Axis", {10, 20});

testing/option_parser.cu

@@ -10,7 +10,7 @@
 //==============================================================================
 // Declare a couple benchmarks for testing:
 void DummyBench(nvbench::state &state) { state.skip("Skipping for testing."); }
-NVBENCH_CREATE(DummyBench);
+NVBENCH_CREATE(DummyBench).clear_devices();
 
 using Ts = nvbench::type_list<void, nvbench::int8_t, nvbench::uint8_t>;
 using Us = nvbench::type_list<bool, nvbench::float32_t, nvbench::float64_t>;
@@ -25,7 +25,8 @@ NVBENCH_CREATE_TEMPLATE(TestBench, NVBENCH_TYPE_AXES(Ts, Us))
   .add_int64_axis("Ints", {42})
   .add_int64_power_of_two_axis("PO2s", {3})
   .add_float64_axis("Floats", {3.14})
-  .add_string_axis("Strings", {"S1"});
+  .add_string_axis("Strings", {"S1"})
+  .clear_devices();
 //==============================================================================
 
 namespace

testing/runner.cu

@@ -69,6 +69,7 @@ void test_empty()
   using runner_type    = nvbench::runner<benchmark_type>;
 
   benchmark_type bench;
+  bench.set_devices(std::vector<int>{});
   runner_type runner{bench};
 
   runner.generate_states();
@@ -85,6 +86,7 @@ void test_non_types()
   using runner_type    = nvbench::runner<benchmark_type>;
 
   benchmark_type bench;
+  bench.set_devices(std::vector<int>{});
   bench.add_int64_axis("Int", {1, 2, 3});
   bench.add_float64_axis("Float", {11.0, 12.0, 13.0});
   bench.add_string_axis("String", {"One", "Two", "Three"});