[ REQ 5171]: Irix 4 vs 5

[burchard at horizon.math.utah.edu]

Currently the Geomview makefiles put Irix 4 and 5 libraries and  
binaries in the same place (with generic target name "sgi").  This  
assumes that no one will have both versions of the operating system  
running simultaneously, or that if they do, they will compile all  
this stuff for Irix 4 and use forward compatibility.  These seem like  
fairly reasonable assumptions, but at the same time Irix 4 and 5 have  
some serious differences at the binary level.  Just like the extent  
of the difference makes it reasonable to have SunOS 4 and 5 (aka.  
Solaris 1 and 2) as different targets, perhaps also Irix 4 and 5?

PB