MC: Put back the MCFragment vtable, so subclasses are destroyed properly (duh).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109649 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index c1365c1..b24c8ca 100644
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -178,6 +178,9 @@
 MCFragment::MCFragment() : Kind(FragmentType(~0)) {
 }
 
+MCFragment::~MCFragment() {
+}
+
 MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
   : Kind(_Kind), Parent(_Parent), Atom(0), EffectiveSize(~UINT64_C(0))
 {