Initial commit of the 'landingpad' instruction.

This implements the 'landingpad' instruction. It's used to indicate that a basic
block is a landing pad. There are several restrictions on its use (see
LangRef.html for more detail). These restrictions allow the exception handling
code to gather the information it needs in a much more sane way.

This patch has the definition, implementation, C interface, parsing, and bitcode
support in it.

llvm-svn: 137501
diff --git a/llvm/lib/VMCore/Instruction.cpp b/llvm/lib/VMCore/Instruction.cpp
index 216bb35..eadcd09 100644
--- a/llvm/lib/VMCore/Instruction.cpp
+++ b/llvm/lib/VMCore/Instruction.cpp
@@ -162,6 +162,7 @@
   case ShuffleVector:  return "shufflevector";
   case ExtractValue:   return "extractvalue";
   case InsertValue:    return "insertvalue";
+  case LandingPad:     return "landingpad";
 
   default: return "<Invalid operator> ";
   }