venus: Make clang happy with strlcpy use

venus: Make clang happy with strlcpy use

clang now expects that strlcpy will always be used to prevent overflow
of the destination string, and gives a warning if the size parameter is
based solely on the length of the source string.

Modify the BreakUpPath function so that it takes the size of the
destination string as an argument, and uses this to limit the amount of
data pasted into it.

Reviewed-on: http://gerrit.openafs.org/7086
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 4e68282e26b0c4569d25d076d54274f0da47a691)

Change-Id: I31003fa06fc331a6313ca17840dcb46f61299921
Reviewed-on: http://gerrit.openafs.org/11845
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>