[clang][dataflow] Use llvm::is_contained()

clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp

 #include "clang/Analysis/FlowSensitive/DataflowEnvironment.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/Type.h"
 #include "clang/Analysis/FlowSensitive/DataflowLattice.h"
 #include "clang/Analysis/FlowSensitive/Value.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>
 #include <memory>
 #include <utility>
 
 namespace clang {
 namespace dataflow {
if (MethodDecl && !MethodDecl->isStatic()) {
           setValue(*ThisPointeeLoc, *ThisPointeeVal);
       }
     }
   }
 }
 
 bool Environment::canDescend(unsigned MaxDepth,
                              const DeclContext *Callee) const {
-  return CallStack.size() <= MaxDepth &&
-         std::find(CallStack.begin(), CallStack.end(), Callee) ==
-             CallStack.end();
+  return CallStack.size() <= MaxDepth && !llvm::is_contained(CallStack, Callee);
 }
 
 Environment Environment::pushCall(const CallExpr *Call) const {
   Environment Env(*this);
 
   // FIXME: Support references here.
   Env.ReturnLoc = getStorageLocation(*Call, SkipPast::Reference);