Still generate switch statement when WARNING about missing statements is given.  It was correct behave when this used to be an error, but not now that it is a warning.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@29279 e7fa87d3-cd2b-0410-9028-fcbf551c1848