hprof generation, not writing the first record

We miss some roots since the first record isn't initialized.

Change-Id: I50c80a701a4ee142c52602b9015f6e93be54da9f
diff --git a/vm/hprof/Hprof.cpp b/vm/hprof/Hprof.cpp
index 4a6b1a6..09890f9 100644
--- a/vm/hprof/Hprof.cpp
+++ b/vm/hprof/Hprof.cpp
@@ -246,6 +246,8 @@
     if (ctx == NULL) {
         return -1;
     }
+    // first record
+    hprofStartNewRecord(ctx, HPROF_TAG_HEAP_DUMP_SEGMENT, HPROF_TIME);
     dvmVisitRoots(hprofRootVisitor, ctx);
     dvmHeapBitmapWalk(dvmHeapSourceGetLiveBits(), hprofBitmapCallback, ctx);
     hprofFinishHeapDump(ctx);