+ .byte DW_CFA_advance_loc4. Call frag_grow with the sum of
+ room needed by frag_more and frag_var to preallocate space
+ ensuring that the DW_CFA_advance_loc4 is in the fixed part
+ of the rs_cfa frag, so that the relax machinery can remove
+ the advance_loc should it advance by zero. */
+ frag_grow (5);