nir: fix nir_variable_data packing

Before:

/* size: 60, cachelines: 1, members: 29 */

After:

/* size: 56, cachelines: 1, members: 29 */

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Rob Clark <robdclark@chromium.org>

src/compiler/nir/nir.h

@@ -404,6 +404,14 @@ typedef struct nir_variable {
        */
       unsigned explicit_offset:1;
 
+      /**
+       * How the variable was declared.  See nir_var_declaration_type.
+       *
+       * This is used to detect variables generated by the compiler, so should
+       * not be visible via the API.
+       */
+      unsigned how_declared:2;
+
       /**
        * \brief Layout qualifier for gl_FragDepth.
        *
@@ -479,14 +487,6 @@ typedef struct nir_variable {
        */
       unsigned xfb_stride;
 
-      /**
-       * How the variable was declared.  See nir_var_declaration_type.
-       *
-       * This is used to detect variables generated by the compiler, so should
-       * not be visible via the API.
-       */
-      unsigned how_declared:2;
-
       /**
        * ARB_shader_image_load_store qualifiers.
        */