SPARC mutex assembler: patches & new code

[fmccor]

If the file gets attached, it is a patch file to enable
mutex (atomic operation) sparc assembler code for sparc-v9/linux systems for
testing, along with
a new source file for src/IceUtil to implement these operations. As described in the
Comments/Ice-for-non-intel... thread, the code is taken from the linux sparc64 kernel
code, and seems to work with Ice.

The new library function is created as a patch to an empty file
src/IceUtil/IceAtomic.c

This code will not work on systems before sparc-v9. It uses instructions they don't have.

This code as written will not work inlined.

This code is untried on solaris, but, as they say, it should work.