Various NX build fixes

src/athena/FileWriterNix.cpp

@@ -7,6 +7,8 @@
 #include "osx_largefilewrapper.h"
 #endif
 
+#include <unistd.h>
+
 namespace athena::io
 {
 FileWriter::FileWriter(std::string_view filename, bool overwrite, bool globalErr)
@@ -82,6 +84,10 @@ void FileWriter::close()
     m_fileHandle = NULL;
 
     std::string tmpFilename = m_filename + '~';
+#ifdef __SWITCH__
+    /* Due to Horizon not being a fully POSIX compatible OS, we need to make sure the file *does not* exist before attempting to rename */
+    unlink(m_filename.c_str());
+#endif
     rename(tmpFilename.c_str(), m_filename.c_str());
 }