(__sread): always read in binary mode
(__swrite): always write in binary mode
* libc/include/stdio.h: no getc/putc macros for cygwin; causes
compatibility issues with different dll versions
* libc/stdio/fopen.c: use __stextmode
* libc/stdio/fdopen.c: ditto
* libc/stdio/freopen.c: ditto
* libc/stdio/findfp.c: set up __SCLE for std{in,out,err}
* libc/stdio/local.h: declare __stextmode
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