[weak vtables] Remove a bunch of weak vtables

This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file. The memory leaks in this version have been fixed. Thanks
Alexey for pointing them out.

Differential Revision: http://llvm-reviews.chandlerc.com/D2068

Reviewed by Andy

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195064 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAtom.cpp b/lib/MC/MCAtom.cpp
index d0a64c3..bc353cd 100644
--- a/lib/MC/MCAtom.cpp
+++ b/lib/MC/MCAtom.cpp
@@ -14,6 +14,9 @@
 
 using namespace llvm;
 
+// Pin the vtable to this file.
+void MCAtom::anchor() {}
+
 void MCAtom::remap(uint64_t NewBegin, uint64_t NewEnd) {
   Parent->remap(this, NewBegin, NewEnd);
 }