When working on fc_sort to try to understand why using /usr/s?bin/... file
contexts has been reported not to work properly [1], I found it frustrating not
to be able to do "tmp/fc_sort my_filecontexts.fc" and see the result printed on
the screen. This patch implements this behavior by making optional the second
argument of fc_sort.
[1] commit 36e2216f8 of contrib repository,
http://git.overlays.gentoo.org/gitweb/?p=proj/hardened-refpolicy.git;a=commit;h=36e2216f82192660d063012e69281f27ba20864b
When running fc_sort on an empty context file, this program uses uninitialized
pointers when accessing to the elements of a list. On my system, it goes in a
very long loop (maybe infinite) because uninitialized fields in malloc'ed
structures happen to contain valid pointers in the heap.
This patch fixes this bug by initializing ->next and ->data fields before they
may be read.
