[memory linux] Properly unlink shared memory

shm_unlink(name) is the proper way to close a shared memory in linux.
Prior to this, xenia was creating and not cleaning up shared memory handle
which would accumulate in /dev/shm. shm_unlink is the proper way of doing
this.
Add filename to CloseFileMappingHandle signature.
Add simple test to open and close.

src/xenia/memory.cc

@@ -115,7 +115,7 @@ Memory::~Memory() {
   // Unmap all views and close mapping.
   if (mapping_) {
     UnmapViews();
-    xe::memory::CloseFileMappingHandle(mapping_);
+    xe::memory::CloseFileMappingHandle(mapping_, file_name_);
     mapping_base_ = nullptr;
     mapping_ = nullptr;
   }