Still generate switch statement when WARNING about missing statements is...

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