[ORC] Fix argv handling in runAsMain / lli.

This fixes an off-by-one error in the argc value computed by runAsMain, and
switches lli back to using the input bitcode (rather than the string "lli") as
the effective program name.

Thanks to Stefan Graenitz for spotting the bug.
diff --git a/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp b/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
index 0a57348..3d97fe9 100644
--- a/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
@@ -42,7 +42,7 @@
   }
   ArgV.push_back(nullptr);
 
-  return Main(Args.size(), ArgV.data());
+  return Main(Args.size() + !!ProgramName, ArgV.data());
 }
 
 CtorDtorIterator::CtorDtorIterator(const GlobalVariable *GV, bool End)