Usage of rint() in gui

[Fred Kiefer]

Two new files are now using rint() in the gui library (NSMatrix and 
NSClipView) as this function is not available on all systems (namely not 
on MS Window) it is not possible to compile gui on such a system. To 
work around this the configuration checks for this function and sets a 
flag whether it is found. This information is not used in these two 
files. So they must be patched just as NSBrowser or NSRulerView.
Or as this becomes more common now, we could move the replacement 
definition of rint() up into the config.h file itself. Any ideas on this 
solution?

Fred