PR# 18302 Use of unsafe routines tempnam and tmpnam

When precompiling EiffelBase or EiffelVision on linux-x86, the linker warns:

C28/Cobj28.o: In function `F904_16897':
(.text+0xea664): warning: the use of `tmpnam' is dangerous, better use `mkstemp'
C15/Cobj15.o: In function `F469_9953':
(.text+0xb3265): warning: the use of `tempnam' is dangerous, better use `mkstemp'

Use of mkstemp or tmpfile eliminates the race condition.  Perhaps there are
good reasons why this has not been changed yet (it might break existing code)
but it seems that ultimately these unsafe routine calls should be replaced
with something safer.