Do not propagate packing qualifiers to scalars or vectors

Packing qualifiers have no practical effect on scalars or vectors
so this is unnecessary and its confusing tools downstream that
consume the AST.

Test/440.frag

@@ -151,3 +151,18 @@ int layer()
 {
     return gl_Layer;
 }
+
+// The std140 layout qualifier should NOT propagate all the way down to
+// the vec3. It is unnecessary and it breaks downstream AST consumers,
+// notably LunarGlass.
+
+struct PointLight_t
+{
+    vec3 vPositionWs ;
+} ;
+
+layout( std140, row_major ) uniform PerViewLightData_t
+{
+
+    PointLight_t g_pointLightData [ 128 ] ;
+} ;