More elegant way of solving #5839 (d_private in sceIoDread)

We flag filesystems as being FAT32 instead of checking for "ms0:".

Core/FileSystems/ISOFileSystem.h

@@ -41,6 +41,7 @@ public:
 	bool     OwnsHandle(u32 handle);
 	int      Ioctl(u32 handle, u32 cmd, u32 indataPtr, u32 inlen, u32 outdataPtr, u32 outlen, int &usec);
 	int      DevType(u32 handle);
+	int      Flags() { return 0; }
 
 	size_t WriteFile(u32 handle, const u8 *pointer, s64 size);
 	bool GetHostPath(const std::string &inpath, std::string &outpath) {return false;}