#277 Fix use of bare `ar` instead of $(AR) in ucsim Makefiles

[Grissess]

Hello!

The title pretty much sums it up; hopefully, this patch makes it easier to use various prefixed tools, like a cross-compiler.

I'm basing this off the newest tarball for download, but please let me know if I need to recreate it ('tis only four lines, after all :)

[Maarten Brock]

I think you should also assign AR at the top of each Makefile with:
AR = @AR@

[Grissess]

Well, I can safely say I learned something about autoconf today :)

Here's a new version, then.

[Daniel Drotos]

Thank you Grisses, I've included your patch in next commit [r9845].