Problem:  filetype: OpenGL Shading Language files are not detected
Solution: detect various file extensions as GLSL filetype, include
          indent and syntax script, do no longer recognize '*.comp'
          as Mason filetype (Gregory Anders)

closes: vim/vim#15317

https://github.com/vim/vim/commit/e4b991ed36f96dd01c6d75e46a04fd1a99180e58