Skip installation of statically linked libraries

[AlexJakeGreen]

The 'all' target may trigger installation into system directories, which needs to be avoided because OpenAL is linked statically.

[Try]

There are still add_subdirectory("thirdparty/libpng") and add_subdirectory("thirdparty/zib"). Is it intentional?

[AlexJakeGreen]

@Try I do not see them in the result file tree, and I think no need to touch. /usr/include/Tempest has a comment that this includes source code but can be improved in future, anyway, it does not bring a harm. doctest, mio are coming from phoenix, that needs to be done separately. include/squish* - can be phoenix, not sure. Will look separately.

This PR works on my side. If it works for Windows and Macos then I think we can merge.

This is the list of files I see installed with this PR:

$ equery f opengothic
 * Searching for opengothic ...
 * Contents of games-rpg/opengothic-9999:
/usr
/usr/bin
/usr/bin/Gothic2Notr
/usr/include
/usr/include/Tempest
/usr/include/Tempest/AbstractGraphicsApi
/usr/include/Tempest/AbstractTextInput
/usr/include/Tempest/AccelerationStructure
/usr/include/Tempest/Application
/usr/include/Tempest/Attachment
/usr/include/Tempest/Brush
/usr/include/Tempest/Builtin
/usr/include/Tempest/Button
/usr/include/Tempest/CheckBox
/usr/include/Tempest/Color
/usr/include/Tempest/ComboBox
/usr/include/Tempest/CommandBuffer
/usr/include/Tempest/ComputePipeline
/usr/include/Tempest/DescriptorSet
/usr/include/Tempest/Device
/usr/include/Tempest/Dialog
/usr/include/Tempest/Dir
/usr/include/Tempest/DirectX12Api
/usr/include/Tempest/Encoder
/usr/include/Tempest/Event
/usr/include/Tempest/EventDispatcher
/usr/include/Tempest/Except
/usr/include/Tempest/Fence
/usr/include/Tempest/File
/usr/include/Tempest/Font
/usr/include/Tempest/IDevice
/usr/include/Tempest/Icon
/usr/include/Tempest/IndexBuffer
/usr/include/Tempest/Label
/usr/include/Tempest/Layout
/usr/include/Tempest/LineEdit
/usr/include/Tempest/ListDelegate
/usr/include/Tempest/ListView
/usr/include/Tempest/Log
/usr/include/Tempest/Matrix4x4
/usr/include/Tempest/MemReader
/usr/include/Tempest/MemWriter
/usr/include/Tempest/Menu
/usr/include/Tempest/MetalApi
/usr/include/Tempest/ODevice
/usr/include/Tempest/PaintDevice
/usr/include/Tempest/Painter
/usr/include/Tempest/Panel
/usr/include/Tempest/Pen
/usr/include/Tempest/PipelineLayout
/usr/include/Tempest/Pixmap
/usr/include/Tempest/Platform
/usr/include/Tempest/Point
/usr/include/Tempest/Rect
/usr/include/Tempest/RenderPipeline
/usr/include/Tempest/RenderState
/usr/include/Tempest/ScrollBar
/usr/include/Tempest/ScrollWidget
/usr/include/Tempest/Shader
/usr/include/Tempest/Shortcut
/usr/include/Tempest/Signal
/usr/include/Tempest/Size
/usr/include/Tempest/SizePolicy
/usr/include/Tempest/Sound
/usr/include/Tempest/SoundDevice
/usr/include/Tempest/SoundEffect
/usr/include/Tempest/Sprite
/usr/include/Tempest/StorageBuffer
/usr/include/Tempest/StorageImage
/usr/include/Tempest/Style
/usr/include/Tempest/Swapchain
/usr/include/Tempest/SystemApi
/usr/include/Tempest/TextCodec
/usr/include/Tempest/TextEdit
/usr/include/Tempest/TextModel
/usr/include/Tempest/Texture2d
/usr/include/Tempest/TextureAtlas
/usr/include/Tempest/Timer
/usr/include/Tempest/Transform
/usr/include/Tempest/UiOverlay
/usr/include/Tempest/UndoStack
/usr/include/Tempest/UniformBuffer
/usr/include/Tempest/Utf8Iterator
/usr/include/Tempest/Vec
/usr/include/Tempest/VectorImage
/usr/include/Tempest/VertexBuffer
/usr/include/Tempest/VulkanApi
/usr/include/Tempest/Widget
/usr/include/Tempest/WidgetState
/usr/include/Tempest/Window
/usr/include/Tempest/ZBuffer
/usr/include/doctest
/usr/include/doctest/doctest.h
/usr/include/mio
/usr/include/mio/detail
/usr/include/mio/detail/mmap.ipp
/usr/include/mio/detail/string_util.hpp
/usr/include/mio/mmap.hpp
/usr/include/mio/page.hpp
/usr/include/mio/shared_mmap.hpp
/usr/include/squish.h
/usr/include/squish_export.h
/usr/lib
/usr/lib64
/usr/lib64/cmake
/usr/lib64/cmake/bullet
/usr/lib64/cmake/bullet/BulletConfig.cmake
/usr/lib64/cmake/bullet/UseBullet.cmake
/usr/lib64/cmake/doctest
/usr/lib64/cmake/doctest/doctest.cmake
/usr/lib64/cmake/doctest/doctestAddTests.cmake
/usr/lib64/cmake/doctest/doctestConfig.cmake
/usr/lib64/cmake/doctest/doctestConfigVersion.cmake
/usr/lib64/cmake/doctest/doctestTargets.cmake
/usr/lib64/libTempest.so
/usr/lib64/libsquish.a
/usr/share
/usr/share/cmake
/usr/share/cmake/mio
/usr/share/cmake/mio/mio-config-version.cmake
/usr/share/cmake/mio/mio-config.cmake
/usr/share/cmake/mio/mio-targets.cmake
/usr/share/doc
/usr/share/doc/opengothic-9999
/usr/share/doc/opengothic-9999/README.md.bz2

[Try]

I've added EXCLUDE_FROM_ALL to other subdirs for consistency. Merged. Thanks!