[PATCH]: fix check-mime-type.pl for changes to 'svnlook proplist' output

Hello,

I recently discovered that the old 'check-mime-type.pl' contrib script is I
had installed on my server was broken when using subversion 1.8.5. I looked
for an updated script in the 1.8.5 branch and in trunk and discovered the
script was also broken in those places as well. After some digging, I found
out when this change happened and patched the script. I suspect (but don't
know for sure) that this only affects subversion 1.8.x.

This patch is from trunk.

[[[
   Fix check-mime-type.pl for output changes to 'svnlook proplist'.

   The output format of 'svnlook proplist' was changed in revision 1416637.

   See also http://svn.haxx.se/dev/archive-2012-11/0510.shtml

   * contrib/hook-scripts/check-mime-type.pl: Fix reading process output from
'svnlook proplist'.
]]]

Regards,

Leo