winrtinstaller: Allow layers from SDK older than RT to be configured for use

Layers from SDK can be used by an RT if their major, minor, and patch numbers
are the same.

For example, if SDK 1.0.5.0 is already installed, and then RT 1.0.5.1 is
installed. During the RT installation, the layer registry entries will be set
to point to the layers in SDK 1.0.5.0.
2 files changed