*: sprintf -> snprintf

*: sprintf -> snprintf

Replace sprintf with snprintf where straightforward to do so.

- sprintf's into local scope buffers of known size are replaced with the
  equivalent snprintf call
- snprintf's into local scope buffers of known size that use the buffer
  size expression now use sizeof(buffer)
- sprintf(buf + strlen(buf), ...) replaced with snprintf() into temp
  buffer followed by strlcat

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>