glslang front-end: Support relaxed error checking for bug 13724...

glslang front-end: Support relaxed error checking for bug 13724 "...initializer must be a constant expression..." because that change breaks existing shipping applications.  (Normal validation for portability testing still gives an error.)


git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@31475 e7fa87d3-cd2b-0410-9028-fcbf551c1848