[NFC][clang] Fix static analyzer concerns

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.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D156133

clang/lib/CodeGen/EHScopeStack.h

@@ -278,6 +278,9 @@ class EHScopeStack {
       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,