[NFC][clang] Fix static analyzer concerns

[Fznamznon]

Summary

EHScopeStack doesn't seem to be intended for copy. It frees memory in
the destructor and doesn't have user-written copy c'tor and assignment
operator, so delete them to avoid using default ones which would do
wrong.

[aaron.ballman]

LGTM!

clang/lib/CodeGen/EHScopeStack.h

 
 public:
   EHScopeStack()
     : StartOfBuffer(nullptr), EndOfBuffer(nullptr), StartOfData(nullptr),
       InnermostNormalCleanup(stable_end()), InnermostEHScope(stable_end()),
       CGF(nullptr) {}
   ~EHScopeStack() { delete[] StartOfBuffer; }
 
+  EHScopeStack(const EHScopeStack &) = delete;
+  EHScopeStack &operator=(const EHScopeStack &) = delete;
+
   /// Push a lazily-created cleanup on the stack.
   template <class T, class... As> void pushCleanup(CleanupKind Kind, As... A) {
     static_assert(alignof(T) <= ScopeStackAlignment,
                   "Cleanup's alignment is too large.");
     void *Buffer = pushCleanup(Kind, sizeof(T));
     Cleanup *Obj = new (Buffer) T(A...);
     (void) Obj;
   }