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/base/mapped_memory_posix.cc

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2014 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. *
  ******************************************************************************
  */
@@ -19,7 +19,7 @@ namespace xe {
 
 class PosixMappedMemory : public MappedMemory {
  public:
-  PosixMappedMemory(const std::wstring& path, Mode mode)
+  PosixMappedMemory(const std::filesystem::path& path, Mode mode)
       : MappedMemory(path, mode), file_handle(nullptr) {}
 
   ~PosixMappedMemory() override {
@@ -34,9 +34,9 @@ class PosixMappedMemory : public MappedMemory {
   FILE* file_handle;
 };
 
-std::unique_ptr<MappedMemory> MappedMemory::Open(const std::wstring& path,
-                                                 Mode mode, size_t offset,
-                                                 size_t length) {
+std::unique_ptr<MappedMemory> MappedMemory::Open(
+    const std::filesystem::path& path, Mode mode, size_t offset,
+    size_t length) {
   const char* mode_str;
   int prot;
   switch (mode) {
@@ -53,7 +53,7 @@ std::unique_ptr<MappedMemory> MappedMemory::Open(const std::wstring& path,
   auto mm =
       std::unique_ptr<PosixMappedMemory>(new PosixMappedMemory(path, mode));
 
-  mm->file_handle = fopen(xe::to_string(path).c_str(), mode_str);
+  mm->file_handle = fopen(path.c_str(), mode_str);
   if (!mm->file_handle) {
     return nullptr;
   }
@@ -77,7 +77,8 @@ std::unique_ptr<MappedMemory> MappedMemory::Open(const std::wstring& path,
 }
 
 std::unique_ptr<ChunkedMappedMemoryWriter> ChunkedMappedMemoryWriter::Open(
-    const std::wstring& path, size_t chunk_size, bool low_address_space) {
+    const std::filesystem::path& path, size_t chunk_size,
+    bool low_address_space) {
   // TODO(DrChat)
   return nullptr;
 }