Provide lib for StandAlone glslangValidator API

[mm-longcheng]

glslangValidator is good as a command line tool. But I want to be able to use the compiler in my own program. Use lib API rather than an independent command line. I tried to modify a copy from StandAlone, but it seems a bit complicated. shaderc is good but i don’t want to introduce too many libraries, glslang is enough.

[mbechard]

You can use glslang as a .lib without any changes. The API is fully exposed, you can copy usage examples from the .exe's workflow and use it in your own code.