[memory] Move "Local\\" prefix to win impl

CreateFileMappingHandle now takes shared memory name without a prefix.
The doc of shm_open recommends not using slashes and prefixing with "/".
The prefixing has been moved to the os implementation layer.
Invocations of CreateFileMappingHandle were all using "Local\\" so these
prefixes were removed.

src/xenia/base/memory_posix.cc

@@ -87,7 +87,8 @@ FileMappingHandle CreateFileMappingHandle(std::wstring path, size_t length,
   }
 
   oflag |= O_CREAT;
-  int ret = shm_open(xe::to_string(path).c_str(), oflag, 0777);
+  std::string full_path = "/" + xe::to_string(path);
+  int ret = shm_open(full_path.c_str(), oflag, 0777);
   if (ret > 0) {
     ftruncate64(ret, length);
   }

src/xenia/base/memory_win.cc

@@ -146,9 +146,10 @@ FileMappingHandle CreateFileMappingHandle(std::wstring path, size_t length,
                                           PageAccess access, bool commit) {
   DWORD protect =
       ToWin32ProtectFlags(access) | (commit ? SEC_COMMIT : SEC_RESERVE);
+  std::wstring full_path = L"Local\\" + path;
   return CreateFileMappingW(INVALID_HANDLE_VALUE, NULL, protect,
                             static_cast<DWORD>(length >> 32),
-                            static_cast<DWORD>(length), path.c_str());
+                            static_cast<DWORD>(length), full_path.c_str());
 }
 
 void CloseFileMappingHandle(FileMappingHandle handle) { CloseHandle(handle); }

src/xenia/cpu/backend/x64/x64_code_cache.cc

@@ -61,7 +61,7 @@ bool X64CodeCache::Initialize() {
   }
 
   // Create mmap file. This allows us to share the code cache with the debugger.
-  file_name_ = std::wstring(L"Local\\xenia_code_cache_") +
+  file_name_ = std::wstring(L"xenia_code_cache_") +
                std::to_wstring(Clock::QueryHostTickCount());
   mapping_ = xe::memory::CreateFileMappingHandle(
       file_name_, kGeneratedCodeSize, xe::memory::PageAccess::kExecuteReadWrite,

src/xenia/memory.cc

@@ -122,7 +122,7 @@ Memory::~Memory() {
 }
 
 bool Memory::Initialize() {
-  file_name_ = std::wstring(L"Local\\xenia_memory_") +
+  file_name_ = std::wstring(L"xenia_memory_") +
                std::to_wstring(Clock::QueryHostTickCount());
 
   // Create main page file-backed mapping. This is all reserved but