Revert "Add support for attribute 'noescape'."

This reverts commit r313722.

It looks like compiler-rt/lib/tsan/rtl/tsan_libdispatch_mac.cc cannot be
compiled because some of the functions declared in the file do not match
the ones in the SDK headers (which are annotated with 'noescape').

llvm-svn: 313725
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index a432c3c..c6988b5 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -455,15 +455,11 @@
 CodeGenTypes::arrangeObjCMessageSendSignature(const ObjCMethodDecl *MD,
                                               QualType receiverType) {
   SmallVector<CanQualType, 16> argTys;
-  SmallVector<FunctionProtoType::ExtParameterInfo, 4> extParamInfos(2);
   argTys.push_back(Context.getCanonicalParamType(receiverType));
   argTys.push_back(Context.getCanonicalParamType(Context.getObjCSelType()));
   // FIXME: Kill copy?
   for (const auto *I : MD->parameters()) {
     argTys.push_back(Context.getCanonicalParamType(I->getType()));
-    auto extParamInfo = FunctionProtoType::ExtParameterInfo().withIsNoEscape(
-        I->hasAttr<NoEscapeAttr>());
-    extParamInfos.push_back(extParamInfo);
   }
 
   FunctionType::ExtInfo einfo;
@@ -479,7 +475,7 @@
 
   return arrangeLLVMFunctionInfo(
       GetReturnType(MD->getReturnType()), /*instanceMethod=*/false,
-      /*chainCall=*/false, argTys, einfo, extParamInfos, required);
+      /*chainCall=*/false, argTys, einfo, {}, required);
 }
 
 const CGFunctionInfo &
@@ -2097,9 +2093,6 @@
       break;
     }
 
-    if (FI.getExtParameterInfo(ArgNo).isNoEscape())
-      Attrs.addAttribute(llvm::Attribute::NoCapture);
-
     if (Attrs.hasAttributes()) {
       unsigned FirstIRArg, NumIRArgs;
       std::tie(FirstIRArg, NumIRArgs) = IRFunctionArgs.getIRArgs(ArgNo);