libutils: give BasicHashtableImpl a virtual destructor

Change-Id: I4ec590b060d732af5fe525670becbe778684247b
diff --git a/libs/utils/BasicHashtable.cpp b/libs/utils/BasicHashtable.cpp
index fd51b7b..491d9e9 100644
--- a/libs/utils/BasicHashtable.cpp
+++ b/libs/utils/BasicHashtable.cpp
@@ -42,6 +42,10 @@
     }
 }
 
+BasicHashtableImpl::~BasicHashtableImpl()
+{
+}
+
 void BasicHashtableImpl::dispose() {
     if (mBuckets) {
         releaseBuckets(mBuckets, mBucketCount);