[opaque pointer types] Pass function types for runtime function calls.

Emit{Nounwind,}RuntimeCall{,OrInvoke} have been modified to take a
FunctionCallee as an argument, and CreateRuntimeFunction has been
modified to return a FunctionCallee. All callers have been updated.

Additionally, CreateBuiltinFunction is removed, as it was redundant
with CreateRuntimeFunction after some previous changes.

Differential Revision: https://reviews.llvm.org/D57668

llvm-svn: 353184
diff --git a/clang/lib/CodeGen/CGAtomic.cpp b/clang/lib/CodeGen/CGAtomic.cpp
index 0f7f5cc..20e5915 100644
--- a/clang/lib/CodeGen/CGAtomic.cpp
+++ b/clang/lib/CodeGen/CGAtomic.cpp
@@ -307,7 +307,7 @@
   const CGFunctionInfo &fnInfo =
     CGF.CGM.getTypes().arrangeBuiltinFunctionCall(resultType, args);
   llvm::FunctionType *fnTy = CGF.CGM.getTypes().GetFunctionType(fnInfo);
-  llvm::Constant *fn = CGF.CGM.CreateRuntimeFunction(fnTy, fnName);
+  llvm::FunctionCallee fn = CGF.CGM.CreateRuntimeFunction(fnTy, fnName);
   auto callee = CGCallee::forDirect(fn);
   return CGF.EmitCall(fnInfo, callee, ReturnValueSlot(), args);
 }