RuntimeDyld: override EH frame registration with trivial version.

llvm-rtdyld was relying on the default memory manager's EH frame registration,
which is host-dependent rather than target-dependent. As a result, big-endian
ELF Mips EH frames were being registered on OS X (and elsewhere). This is a
really bad idea.

llvm-svn: 238951
diff --git a/llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp b/llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp
index bef6a1a..f857b2e 100644
--- a/llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp
+++ b/llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp
@@ -139,6 +139,11 @@
   // explicit cache flush, otherwise JIT code manipulations (like resolved
   // relocations) will get to the data cache but not to the instruction cache.
   virtual void invalidateInstructionCache();
+
+  void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
+                        size_t Size) override {}
+  void deregisterEHFrames(uint8_t *Addr, uint64_t LoadAddr,
+                          size_t Size) override {}
 };
 
 uint8_t *TrivialMemoryManager::allocateCodeSection(uintptr_t Size,