C++17ification.

C++17ification!

- Filesystem interaction now uses std::filesystem::path.
- Usage of const char*, std::string have been changed to
  std::string_view where appropriate.
- Usage of printf-style functions changed to use fmt.

src/xenia/cpu/processor.cc

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2013 Ben Vanik. All rights reserved.                             *
+ * Copyright 2020 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */
@@ -42,8 +42,8 @@
 
 DEFINE_bool(debug, DEFAULT_DEBUG_FLAG,
             "Allow debugging and retain debug information.", "General");
-DEFINE_string(trace_function_data_path, "", "File to write trace data to.",
-              "CPU");
+DEFINE_path(trace_function_data_path, "", "File to write trace data to.",
+            "CPU");
 DEFINE_bool(break_on_start, false, "Break into the debugger on startup.",
             "CPU");
 
@@ -140,7 +140,7 @@ bool Processor::Setup(std::unique_ptr<backend::Backend> backend) {
   }
 
   // Open the trace data path, if requested.
-  functions_trace_path_ = xe::to_wstring(cvars::trace_function_data_path);
+  functions_trace_path_ = cvars::trace_function_data_path;
   if (!functions_trace_path_.empty()) {
     functions_trace_file_ = ChunkedMappedMemoryWriter::Open(
         functions_trace_path_, 32 * 1024 * 1024, true);
@@ -167,7 +167,7 @@ bool Processor::AddModule(std::unique_ptr<Module> module) {
   return true;
 }
 
-Module* Processor::GetModule(const char* name) {
+Module* Processor::GetModule(const std::string_view name) {
   auto global_lock = global_critical_region_.Acquire();
   for (const auto& module : modules_) {
     if (module->name() == name) {
@@ -186,7 +186,7 @@ std::vector<Module*> Processor::GetModules() {
   return clone;
 }
 
-Function* Processor::DefineBuiltin(const std::string& name,
+Function* Processor::DefineBuiltin(const std::string_view name,
                                    BuiltinFunction::Handler handler, void* arg0,
                                    void* arg1) {
   uint32_t address = next_builtin_address_;