[PATCH] Handle memory allocation failure.

[Jim Meyering]

Hello,

I spotted a few unchecked memory allocation failures early this week
(here's the one that hasn't been taken yet)
  http://article.gmane.org/gmane.linux.kernel/634811
and went looking for more.  I found and fixed seven more:
[Thanks to Markus Armbruster for a rigorous review. ]

FYI, my first crack at cleaning up v9fs_parse_options
removed the match_strdup call altogether, but was more
invasive in that it added a new function, match_strcmp and
made the existing match_number function public.
The patch below just handles the match_strdup failure.

Also, with a new match_strlcpy function, one could avoid the
match_strdup call in fs/affs/super.c, and with a new
match_simple_strtoll function, one could avoid a few more
memory allocations.  That's for another day...

Here's the patch:

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