Fix FreeBSD/Clang C++ error

/usr/include/c++/v1/iterator:1168:87: error: expected unqualified-id
  ...&& traits_type::eq_int_type(__sbuf_->sputc(__c), traits_type::eof()))
                                                                   ^
/src/sbbs3/../xpdev/filewrap.h:124:21: note:

      expanded from macro 'eof'
        #define eof(fd)                         (tell(fd)==filelength(fd))
  
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passed #32854
FreeBSD
jsdoor-freebsd

00:04:16

passed #32855
Linux
jsdoor-linux

00:06:58

passed #32857
FreeBSD
jsdoor-windows

00:01:56

passed #32849
FreeBSD
sbbs-freebsd

00:05:47

passed #32844
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sbbs-linux

00:10:55

passed #32847
Windows
sbbs-windows

00:05:42

passed #32856
FreeBSD
sexpots-freebsd

00:00:12

passed #32845
Linux
sexpots-linux

00:00:19

passed #32848
Windows
sexpots-windows

00:00:25

passed #32852
FreeBSD
syncdraw-freebsd

00:00:27

passed #32853
Linux
syncdraw-linux

00:01:00

passed #32850
FreeBSD
syncterm-freebsd

00:01:03

passed #32846
Linux
syncterm-linux

00:02:53

passed #32851
FreeBSD
syncterm-windows

00:01:50