3 minor fixups where sprintf() was used instead of snprintf() with

3 minor fixups where sprintf() was used instead of snprintf() with
a known max length.  Additionally the function return value is cast
to void to make it explicit that the value is not needed.

git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@172 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c