Improve separation between build and install

[kkaefer]

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Currently, if a binary package is not available, Mason tries to build the package from source. However, the system may not be set up to actually compile that package. Instead, we should make a clearer distinction between using a library and building a library.

[ljbade]

So are you proposing it to fail if it can't find a pre-built library?

[springmeyer]

removing the fallback to a compile if the install fails would be fine.

[mikemorris]

In https://github.com/mapbox/mapbox-gl-native/issues/2346#issuecomment-141191520 I found that requiring multiple mason packages that fall back to a build can end up setting an incorrect MASON_BUILD_PATH.