(LLVM svn up) Generalize RuntimeFunctions to RuntimeGlobals and add

(LLVM svn up) Generalize RuntimeFunctions to RuntimeGlobals and add
CodeGenModule::CreateRuntimeVariable.

 - No real functionality change; although we now assert on silly
   things like:
--
int objc_exception_throw;
void f0() { @throw(@"A"); }
--
   instead of accepting it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@66292 91177308-0d34-0410-b5e6-96231b3b80d8