nir: add matrix_layout to nir_variable data

This will be used by the following patch.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4623>

src/compiler/glsl/glsl_to_nir.cpp

@@ -464,6 +464,7 @@ nir_visitor::visit(ir_variable *ir)
 
    var->data.precision = ir->data.precision;
    var->data.explicit_location = ir->data.explicit_location;
+   var->data.matrix_layout = ir->data.matrix_layout;
    var->data.from_named_ifc_block = ir->data.from_named_ifc_block;
    var->data.compact = false;
 

src/compiler/nir/nir.h

@@ -439,6 +439,11 @@ typedef struct nir_variable {
        */
       unsigned explicit_offset:1;
 
+      /**
+       * Layout of the matrix.  Uses glsl_matrix_layout values.
+       */
+      unsigned matrix_layout:2;
+
       /**
        * Non-zero if this variable was created by lowering a named interface
        * block.