Fix some of the memcheck errors found in the JIT unittests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95856 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/DerivedTypes.h

@@ -496,6 +496,7 @@ public:
 /// OpaqueType - Class to represent abstract types
 ///
 class OpaqueType : public DerivedType {
+  friend class LLVMContextImpl;
   OpaqueType(const OpaqueType &);                   // DO NOT IMPLEMENT
   const OpaqueType &operator=(const OpaqueType &);  // DO NOT IMPLEMENT
   OpaqueType(LLVMContext &C);