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 jsdoor-freebsd #32854
FreeBSD

00:04:16

passed jsdoor-linux #32855
Linux

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passed jsdoor-windows #32857
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passed sbbs-freebsd #32849
FreeBSD

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passed sbbs-linux #32844
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passed sbbs-windows #32847
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passed sexpots-freebsd #32856
FreeBSD

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passed sexpots-linux #32845
Linux

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passed sexpots-windows #32848
Windows

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passed syncdraw-freebsd #32852
FreeBSD

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passed syncdraw-linux #32853
Linux

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passed syncterm-freebsd #32850
FreeBSD

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passed syncterm-linux #32846
Linux

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passed syncterm-windows #32851
FreeBSD

00:01:50