Som changes made to the garbage collector to accommodate the sather compiler.

   Jeff Bilmes

In gc.h, after each new allocation, hincr is multiplied
by the #defined constants HINCR_MULT/HINCR_DIV. For Sather, this ratio has
been changed from 3/2 to the constant '2'.

In alloc.c, on Sun systems, the vadvise(2) system call is used around
the gcollect() function.

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Changed the names of mach dependent asm files to allow untar'ing on
SysV hosts with 14 char filename restriction.

Moreover gc.h and mach_dep.c contain Michael Arnoldus' 
Patches for SCO UNIX SYSV R3.2. Note that we replaced the struct
"obj" by "gc_obj" to avoid a name conflict in SysV.


