libc: -Zbin-files doesn't work on stdin/out/err - init order

[bird]

There is a init order problem with -Zbin-files when LIBC is linked dynamically. stdio.c is called long before any constructors in the executable is invoked, so the bin-files flag flipping won't apply to any handles opened or initialized there.

[froloff]

May be it will be usefull to test if stdin/stdout isatty(), before changing mode?

[bird]

It appears this borken all together. The best workaround is to use O_BINARY and O_TEXT when those applies instead of -Zbin-files.