Add NeXT runtime support for generating methods.

Add NeXT runtime support for generating methods.

Change CodeGenFunction::EmitParmDecl to take either a ParmVarDecl or an
  ImplicitParamDecl.

Drop hasAggregateLLVMType from CodeGenModule.cpp (use version in
  CodeGenFunction).

Change the Objective-C method generation to use EmitParmDecl for
  implicit parameters.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@54838 91177308-0d34-0410-b5e6-96231b3b80d8