Add support for "-Ifoo" in addition to "-I foo"


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26487 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/TableGen.cpp b/utils/TableGen/TableGen.cpp
index 1007e1b..366af85 100644
--- a/utils/TableGen/TableGen.cpp
+++ b/utils/TableGen/TableGen.cpp
@@ -84,7 +84,7 @@
 
   cl::list<std::string>
   IncludeDirs("I", cl::desc("Directory of include files"),
-              cl::value_desc("directory"));
+              cl::value_desc("directory"), cl::Prefix);
 }
 
 namespace llvm {