fixed doc builder warnings; make sure the tests give reasonable results when OpenCL is not available

it uses HAVE_CUDA, HAVE_NVCUVID, etc. macroses

Looks like we don't actually use them; when creating precompiled headers
with Visual C++, a dummy .cpp is created at build time.

Turns out, you can't use preprocessor directives inside macro arguments.
Who'd have thought?

Now it allows choosing between arbitrary implementation variants.

This reverts commit fba72cb6, reversing
changes made to 02131ffb.

* disabled warnings from thrust
* fixed warnings from ts_gtest.h
* possibly fixed superres compilation in Debug mode on Windows

e.g. <opencv2/core/core.hpp> become <opencv2/core.hpp>

Also renamed <opencv2/core/opengl_interop.hpp> to <opencv2/core/opengl.hpp>

Made all STL usages explicit to be able automatically find all usages of
particular class or function.