Add HelloPass stuff

CMakeLists.txt

+find_package(LLVM REQUIRED CONFIG)
+
+add_definitions(${LLVM_DEFINITIONS})
+include_directories(${LLVM_INCLUDE_DIRS})
+
+add_subdirectory(skeleton)  # Use your pass name here.

skeleton/CMakeLists.txt

+add_library(SkeletonPass MODULE Skeleton.cpp)

skeleton/Skeleton.cpp

+#include "llvm/Pass.h"
+#include "llvm/Function.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+namespace {
+  struct Hello : public FunctionPass {
+    static char ID;
+    Hello() : FunctionPass(ID) {}
+
+    virtual bool runOnFunction(Function &F) {
+      errs() << "Hello: ";
+      errs().write_escaped(F.getName()) << '\n';
+      return false;
+    }
+  };
+}
+
+char Hello::ID = 0;
+static RegisterPass<Hello> X("hello", "Hello World Pass");