add new -DBUILD_UTILS option to cmake

[jbathegit]

Fixes #378

[jbathegit]

Hey @AlexanderRichert-NOAA, the Spack/recipe-check test is now failing b/c of the new -DBUILD_UTILS option:

I'm not sure what the best default would be to set this to in spack/package.py, so would you please take a look at this?

And BTW, we already have a separate -DBUILD_TESTING option available in the library, so how exactly does that relate to the BUILD_TESTS option that's also defined in spack/package.py? Or are they two separate settings for different purposes? Again, BUILD_TESTING is what is used throughout the rest (i.e. non-Python parts) of the library :-)

[AlexanderRichert-NOAA]

I added a variant corresponding with BUILD_UTILS to the Spack recipe. See my PR #605 that points to your jba_utilsoption branch.

As for "BUILD_TESTS," it is in the recipe because that's the option was called in older versions; with the newer versions it just gets ignored.

[jbathegit]

Got it - thanks Alex!

[jbathegit]

Thanks again @AlexanderRichert-NOAA for your help to resolve this!

When you get a chance, could you (or @edwardhartnett or @jack-woollen) please review and approve the rest of this PR so we can get it merged?