Add missing vtable anchors

Summary: This patch adds anchor() for MemoryBuffer, raw_fd_ostream, RTDyldMemoryManager, SectionMemoryManager, etc.

Reviewers: jlebar, eli.friedman, dblaikie

Reviewed By: dblaikie

Subscribers: mehdi_amini, mgorny, dblaikie, weimingz, llvm-commits

Differential Revision: https://reviews.llvm.org/D45244

llvm-svn: 329861
diff --git a/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp b/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
index 2dc66a1..05ab4a0 100644
--- a/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
+++ b/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
@@ -232,6 +232,8 @@
 
 SectionMemoryManager::MemoryMapper::~MemoryMapper() {}
 
+void SectionMemoryManager::anchor() {}
+
 namespace {
 // Trivial implementation of SectionMemoryManager::MemoryMapper that just calls
 // into sys::Memory.