MCStreamer: Also clear vector of W64UnwindInfos on reset().

Patch by Kai Nacke!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181363 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 4839c34..8f1895e 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -35,6 +35,7 @@
 void MCStreamer::reset() {
   for (unsigned i = 0; i < getNumW64UnwindInfos(); ++i)
     delete W64UnwindInfos[i];
+  W64UnwindInfos.clear();
   EmitEHFrame = true;
   EmitDebugFrame = false;
   CurrentW64UnwindInfo = 0;