meshoptimizer and MVT support

[devil-darkside]

Even if the meshoptimizer and protobuf libraries were installed through vcpkg, the features have not been enabled by the CMAKE configuration.

From Visual Studio output:

"Warning: MeshOptimizer not available. CompressedArray classes will not be available."

osgEarth was not built with MVT support src\applications\osgearth_mvtindex\osgearth_mvtindex.cpp(124,5): error C2065: 'MVTFeatureSource': undeclared identifier src\applications\osgearth_mvtindex\osgearth_mvtindex.cpp(124,23): error C2065: 'input': undeclared identifier src\applications\osgearth_mvtindex\osgearth_mvtindex.cpp(124,35): error C2061: syntax error: identifier 'MVTFeatureSource' src\applications\osgearth_mvtindex\osgearth_mvtindex.cpp(125,5): error C2065: 'input': undeclared identifier src\applications\osgearth_mvtindex\osgearth_mvtindex.cpp(126,9): error C2065: 'input': undeclared identifier src\applications\osgearth_mvtindex\osgearth_mvtindex.cpp(128,73): error C2065: 'input': undeclared identifier src\applications\osgearth_mvtindex\osgearth_mvtindex.cpp(181,5): error C2065: 'input': undeclared identifier src\applications\osgearth_mvtindex\osgearth_mvtindex.cpp(195,28): error C2065: 'input': undeclared identifier

[devil-darkside]

Errors in "BuildConfig". Solved.