Modern CMake find module for GLSLang. Should work on any platform, but tested only on linux.
Add this repo root directory into your cmake find path like this:
LIST(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
Then require it like this:
find_package(GLSLang COMPONENTS GLSLang SPRIV)
You should already know a bit about CMake stuff, like REQUIRED, QUIET and similliar things. Only one thing that may be new for you is COMPONENTS dirictive. It's required and can be either GLSLang, SPIRV or both (like in example). It defines which libs will be searched and which targets will be defined.
Link to GLSLang::GLSLang or GLSLang::SPIRV depending on which libs you required and need.
As a sidenote, module don't define any vars: use targets to link to library and if(TARGET GLSLang::COMPONENT) to check is library available.