Library API for accessing glslc functionality - shared libraries

 glslc wraps around core functionality in glslang and SPIRV-Tools. glslc and
 its library aims to provide:
    - a command line compiler with GCC- and Clang-like usage, for better
    integration with build systems;
    - an API where functionality can be added without breaking existing clients;
    - an API supporting standard concurrency patterns across multiple operating
    systems;
    - increased functionality such as file #include support.
 .
 This package contains shared libraries.