nir: Add a deref_instr_has_indirect helper

Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/nir/nir.h

@@ -987,6 +987,8 @@ nir_deref_instr_get_variable(const nir_deref_instr *instr)
    return instr->var;
 }
 
+bool nir_deref_instr_has_indirect(nir_deref_instr *instr);
+
 bool nir_deref_instr_remove_if_unused(nir_deref_instr *instr);
 
 typedef struct {