This reverts commit 1f8f7e2d54, "* libc/stdio/refill.c (__srefill):
Try again after EOF on Cygwin." If EOF is set on a file, the stdio
input functions will now immediately return EOF rather than trying
again to read. This aligns Cygwin's behavior to that of Linux.
Addresses: https://cygwin.com/pipermail/cygwin/2022-June/251672.html