fopen() and friends don't accept binary modes

[Deek]

OS-9, like Unix, makes no distinction between text and binary files; but when ANSI showed up, it specified that fopen needs to accept b even if it makes no difference, for portability with other systems that make a distinction between text and binary files. But when Kreider fopen() encounters b in a mode string, it fails with an Error 203 (Bad Mode) in errno.