Squashed 'Core/CppMicroServices/' changes from 2bddc98..8dcbc82

8dcbc82 Added include which is not transitively included in MSVS 2010 and later
f0199b8 Don't track invalid service references at all.
1b34711 Align ServiceTracker API by return std::vector.
d21222b Check for invalid references in operators.
2d40eb1 Silence Clang warning about unused member.

git-subtree-dir: Core/CppMicroServices
git-subtree-split: 8dcbc82d75e1a2a18c488e2c0103ee6b7ad67ee6