fix: 优化 label 组件鼠标显示效果

src/core/view/components/label/index.vue

 <template>
   <uni-label
+    :class="{'uni-label-pointer':pointer}"
     v-on="$listeners"
     @click="_onClick">
     <slot />
@@ -18,6 +19,11 @@ export default {
       default: ''
     }
   },
+  computed: {
+    pointer () {
+      return this.for || (this.$slots.default && this.$slots.default.length)
+    }
+  },
   methods: {
     _onClick ($event) {
       let stopPropagation = /^uni-(checkbox|radio|switch)-/.test($event.target.className)
@@ -38,5 +44,7 @@ export default {
 }
 </script>
 <style>
-
-</style>
+.uni-label-pointer {
+  cursor: pointer;
+}
+</style>