nir: remove unused nir_variable fields

These are used in GLSL IR to removed unused varyings and match
transform feedback variables. There is no need to use these in NIR.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/nir/nir.h

@@ -223,24 +223,6 @@ typedef struct nir_variable {
        */
       unsigned location_frac:2;
 
-      /**
-       * Non-zero if this variable was created by lowering a named interface
-       * block which was not an array.
-       *
-       * Note that this variable and \c from_named_ifc_block_array will never
-       * both be non-zero.
-       */
-      unsigned from_named_ifc_block_nonarray:1;
-
-      /**
-       * Non-zero if this variable was created by lowering a named interface
-       * block which was an array.
-       *
-       * Note that this variable and \c from_named_ifc_block_nonarray will never
-       * both be non-zero.
-       */
-      unsigned from_named_ifc_block_array:1;
-
       /**
        * \brief Layout qualifier for gl_FragDepth.
        *