PATCH: fix sim/i960/Makefile.in for CGEN

[Dave Brolley]

Greg McGary wrote:
> 
> The `@true' commands defeat VPATH and render sim/i960 uncompilable
> when $(srcdir) != $(builddir).  fr30 and m32r already have this fix,
> though it's done by commenting-out the `@true' line (IMO, those should
> be removed entirely).

Yeah -- I only commented them out because I wasn't sure it wasn't
some kind of bug in my version of make. What is @true supposed to
do anyway, and why does it mess up VPATH?

Dave