Compilation of xgrass on RS600

[Randy Hills]

The following is a bug fix for xgrass in xc.name.c that I've had to apply
in the RS6000 environment in order to get text strings in menus to be
readable.  My feeling is the fix is applicable to other environments, the 
ifdef was put there to retain the original code.  The following is a diff of
the old and new routines:

%  diff xc.name.c.orig xc.name.c
 
259a260,262
> #ifdef _AIX
>                     static char retBuf[256];
> #else
260a264
> #endif

I've also submitted this to the grass bug mailing list.