vbscript: Use DEFAULT_UNREACHABLE macro where appropriate.

dlls/vbscript/compile.c

@@ -98,8 +98,7 @@ static void dump_instr_arg(instr_arg_type_t type, instr_arg_t *arg)
         break;
     case ARG_NONE:
         break;
-    default:
-        assert(0);
+    DEFAULT_UNREACHABLE;
     }
 }
 
@@ -1398,9 +1397,7 @@ static HRESULT create_class_funcprop(compile_ctx_t *ctx, function_decl_t *func_d
         case FUNC_PROPSET:
             invoke_type = VBDISP_SET;
             break;
-        default:
-            assert(0);
-            return E_FAIL;
+        DEFAULT_UNREACHABLE;
         }
 
         assert(!desc->entries[invoke_type]);

dlls/vbscript/global.c

@@ -1010,9 +1010,7 @@ static HRESULT Global_InStr(vbdisp_t *This, VARIANT *args, unsigned args_cnt, VA
     case 4:
         FIXME("unsupported compare argument %s\n", debugstr_variant(args));
         return E_NOTIMPL;
-    default:
-        assert(0);
-        return E_FAIL;
+    DEFAULT_UNREACHABLE;
     }
 
     if(startv) {

dlls/vbscript/vbdisp.c

@@ -172,8 +172,7 @@ static HRESULT invoke_builtin(vbdisp_t *This, const builtin_prop_t *prop, WORD f
                 V_BSTR(res) = ret;
                 break;
             }
-            default:
-                assert(0);
+            DEFAULT_UNREACHABLE;
             }
             return S_OK;
         }

dlls/vbscript/vbscript.c

@@ -216,8 +216,7 @@ static void decrease_state(VBScript *This, SCRIPTSTATE state)
         break;
     case SCRIPTSTATE_CLOSED:
         break;
-    default:
-        assert(0);
+    DEFAULT_UNREACHABLE;
     }
 }