StatSchema support DropIndex

src/main/java/com/alibaba/druid/stat/TableStat.java

@@ -33,6 +33,15 @@ public class TableStat {
     int createCount      = 0;
     int alterCount       = 0;
     int createIndexCount = 0;
+    int dropIndexCount   = 0;
+
+    public int getDropIndexCount() {
+        return dropIndexCount;
+    }
+
+    public void incrementDropIndexCount() {
+        this.dropIndexCount++;
+    }
 
     public int getCreateIndexCount() {
         return createIndexCount;
@@ -155,6 +164,9 @@ public class TableStat {
         if (createIndexCount > 0) {
             buf.append("CreateIndex");
         }
+        if (dropIndexCount > 0) {
+            buf.append("DropIndex");
+        }
 
         return buf.toString();
     }
@@ -497,7 +509,7 @@ public class TableStat {
         Merge(16), //
         Truncate(32), //
         Alter(64), //
-        Drop(128);
+        Drop(128), DropIndex(256); //
 
         public final int mark;