Fix for bug #3019 : That incorrectly removed perVertexEXT qualifier as arrayed IO

This bug got introduced as part of EXT_mesh_shader changes 228c672
Also updated barycentric test cases to add coverage for multiple pervertexEXT array inputs

glslang/Include/Types.h

@@ -875,7 +875,7 @@ public:
         case EShLangTessEvaluation:
             return ! patch && isPipeInput();
         case EShLangFragment:
-            return pervertexNV && isPipeInput();
+            return (pervertexNV || pervertexEXT) && isPipeInput();
         case EShLangMesh:
             return ! perTaskNV && isPipeOutput();