[LTO API] fix memory leakage introduced at r230290.

r230290 released the LLVM module but not the LTOModule.

rdar://19024554


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230544 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/LTO/LTOCodeGenerator.h

@@ -155,6 +155,7 @@ private:
   typedef StringMap<uint8_t> StringSet;
 
   void initialize();
+  void destroyMergedModule();
   std::unique_ptr<LLVMContext> OwnedContext;
   LLVMContext &Context;
   Linker IRLinker;
@@ -172,6 +173,7 @@ private:
   TargetOptions Options;
   lto_diagnostic_handler_t DiagHandler;
   void *DiagContext;
+  LTOModule *OwnedModule;
 };
 }
 #endif