[CIR][CodeGen][NFC] Implement a missing function

This was declared but never implemented. Upon first usage in a later
commit this fails to link.

Reviewers: bcardosolopes, smeenai

Reviewed By: smeenai

Pull Request: #1024

Author: lanza

clang/lib/CIR/CodeGen/CIRGenCleanup.cpp

@@ -707,4 +707,15 @@ void EHScopeStack::pushTerminate() {
   char *Buffer = allocate(EHTerminateScope::getSize());
   new (Buffer) EHTerminateScope(InnermostEHScope);
   InnermostEHScope = stable_begin();
-}
+}
+
+bool EHScopeStack::containsOnlyLifetimeMarkers(
+    EHScopeStack::stable_iterator old) const {
+  for (EHScopeStack::iterator it = begin(); stabilize(it) != old; it++) {
+    EHCleanupScope *cleanup = dyn_cast<EHCleanupScope>(&*it);
+    if (!cleanup || !cleanup->isLifetimeMarker())
+      return false;
+  }
+
+  return true;
+}