win32: remove an unneeded mechanism

Instead of relying on the macro-defined lseek(), just use _lseeki64
directly, and avoid a minor mess.

osdep/io.c

@@ -17,8 +17,6 @@
  * You should have received a copy of the GNU General Public License along
  * with mplayer2.  If not, see <http://www.gnu.org/licenses/>.
  */
-#define MP_HIDE_IO_REPLACEMENTS
-
 #include <unistd.h>
 #include <errno.h>
 
@@ -428,7 +426,7 @@ off_t mp_lseek(int fd, off_t offset, int whence)
         errno = ESPIPE;
         return (off_t)-1;
     }
-    return lseek(fd, offset, whence);
+    return _lseeki64(fd, offset, whence);
 }
 
 #endif // __MINGW32__

osdep/io.h

@@ -124,15 +124,13 @@ void mp_globfree(mp_glob_t *pglob);
 #define tmpfile(...) mp_tmpfile(__VA_ARGS__)
 #define getenv(...) mp_getenv(__VA_ARGS__)
 
-// Things MinGW defines as macros, and which we want to override only for the
-// user, and not io.c (which wants the original definition).
-#ifndef MP_HIDE_IO_REPLACEMENTS
 #undef lseek
 #define lseek(...) mp_lseek(__VA_ARGS__)
-#endif
 
+// Affects both "stat()" and "struct stat".
 #undef stat
 #define stat mp_stat
+
 #undef fstat
 #define fstat(...) mp_fstat(__VA_ARGS__)