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))
  

src/xpdev/filewrap.h

@@ -121,7 +121,9 @@
 
 	#define chsize(fd,size)		ftruncate(fd,size)
 	#define tell(fd)			lseek(fd,0,SEEK_CUR)
+	#ifndef __cplusplus	// Conflict with FreeBSD /usr/include/c++/v1/iterator
 		#define eof(fd)			(tell(fd)==filelength(fd))
+	#endif
 
 #elif defined(__OS2__)