add vendor

vendor/github.com/gin-gonic/contrib/expvar/expvar.go

@@ -0,0 +1,26 @@
+package expvar
+
+import (
+	"expvar"
+	"fmt"
+
+	"github.com/gin-gonic/gin"
+)
+
+func Handler() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		w := c.Writer
+		c.Header("Content-Type", "application/json; charset=utf-8")
+		w.Write([]byte("{\n"))
+		first := true
+		expvar.Do(func(kv expvar.KeyValue) {
+			if !first {
+				w.Write([]byte(",\n"))
+			}
+			first = false
+			fmt.Fprintf(w, "%q: %s", kv.Key, kv.Value)
+		})
+		w.Write([]byte("\n}\n"))
+		c.AbortWithStatus(200)
+	}
+}