[Mochi-devel] one less boost dependency

[Latham, Robert J.]

As Phil mentioned last month, we were looking at how we can eliminate
an explicit dependency on boost.

Jerome helped me tidy up that work and now the Boost Preprocessor
macros we need are all incorporated into mercury.   You can still
request "system boost" if you want/need that for any reason.

I've updated our spack package to remove the boost dependency.

We do still use boost in our 'sds-keyval' package (and anything that
depends on it).  I think we can reimplement boost functionallity there
without too much work, but we haven't dont that yet.

==rob