Linking warning about "tmpnam"

When linking CGM applications, sometimes you get the link warning that looks something like:

iGeom_CGMA.cc:(.text+0xa122): warning: the use of `tmpnam' is dangerous, better use `mkstemp'

This is a known problem, due to the use of a "tmpnam" function for naming a temporary file. We have not seen any problem with its use in the past.