tccgen: cleanup _Alignas implementation

Remove the unneeded compare, introduced in the recent _Alignas update.
sorry for that

--
bye bye Detlef

tccgen.c

@@ -4477,7 +4477,7 @@ static int parse_btype(CType *type, AttributeDef *ad)
                     type_size(&type1, &n);
               } else {
                   n = expr_const();
-                  if (n < 0 || (n > 1 && (n & (n - 1)) != 0))
+                  if (n < 0 || (n & (n - 1)) != 0)
                     tcc_error("alignment must be a positive power of two");
               }
               skip(')');