bug#12225: One test failed on Solaris 10

[Stefano Lattarini]

>
> $ make -j16 check
> ...
FAIL: df/no-mtab-status

And the same failure (and only that) takes place if the Sun C compiler
is used (version "Sun C 5.9 SunOS_i386 Patch 124868-15 2010/08/11").

Regards,
  Stefano