2013-04-10  Bin Cheng  <bin.cheng@arm.com>
        * acconfig.h (_FSEEK_OPTIMIZATION): Undef
        * newlib.hin (_FSEEK_OPTIMIZATION): Undef
        * configure.in (--disable-newlib-fseek-optimization): New option.
        * configure: Regenerated.
        * libc/stdio/fflush.c (__sflush_r): Use _FSEEK_OPTIMIZATION to
        control fseek optimization.
        * libc/stdio/fseeko.c (_fseeko_r): Ditto.
        * libc/stdio/makebuf.c (__smakebuf_r): Ditto.
        * libc/stdio64/fseeko64.c (_fseeko64_r): Ditto.