fileops: Don't process ,ccs= as individual mode flags (BZ#18906)

In processing the first 7 individual characters of the mode for fopen
if ,ccs= is used those characters will be processed as well.  Stop
processing individual mode flags once a comma is encountered.  This has
the effect of requiring ,ccs= to be the last mode flag in the mode
string.  Add a testcase to check that the ,ccs= mode flag is not
processed as individual mode flags.

Reviewed-by: DJ Delorie <dj@redhat.com>