* moves dolphin-specific settings out of Base.props
* creates exports.props for externals, allowing to easily import
individual Externals
* corrects some cruft that accumulated and probably contributed
to msbuild overbuilding
This updates glslang to commit 9bb8cfffb0eed010e07132282c41d73064a7a609
which is the current version listed in the known_good.json file for the
version 1.3.212 of the Vulkan-ValidationLayers repo.
This updates glslang to commit 4fc7a33910fb8e40b970d160e1b38ab3f67fe0f3
which is the current version listed in the known_good.json file for the
version 1.2.131.2 of the Vulkan-ValidationLayers repo.
* -Wno-unused-but-set-variable: only set this flag with gcc, otherwise
clang will issue warnings about the warning option being unknown :)
(-Wunknown-warning-option)
* -Wmissing-variable-declarations: clang warns about missing extern
declarations for non-static variables.
