QtLocation cannot be used with qmlsc in direct mode

QtLocation's way of splitting the qml plugins from the rest of the library and generating only plugins without backing libraries is fundamentally incompatible with direct mode.

In direct mode we need to:

1. Include the library's (possibly private) headers. If all QML types are defined in a header "location.h" that lives in a plugin we cannot do that. location.h is not installed after all.
2. Link the library into user applications. If all QML types live in a plugin, we cannot sensibly do that. I know it is possible to link plugins, but users should not be required to. Having to use private API is bad enough.