[Buildroot] zcat default

[Heikki Lindholm]

Hi,

BR2_ZCAT defaults to zcat, and it is basically always used to extract 
files with .gz suffix. POSIX zcat [1] is specified to append .Z to 
filenames that don't already have such suffix. This is also the 
behaviour on Mac OS X. Therefore, it would make sense to use gunzip -c 
or gzip -dc as a default instead.

[1] http://www.opengroup.org/onlinepubs/000095399/utilities/zcat.html

-- Heikki Lindholm