Update to latest LLVM code (#88)

* Update to latest LLVM code.

* Add LLVM's raw_ostream.

* MathExtras.h: Include cmath for log2.

src/llvm/raw_os_ostream.cpp

@@ -0,0 +1,30 @@
+//===--- raw_os_ostream.cpp - Implement the raw_os_ostream class ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This implements support adapting raw_ostream to std::ostream.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/raw_os_ostream.h"
+#include <ostream>
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+//  raw_os_ostream
+//===----------------------------------------------------------------------===//
+
+raw_os_ostream::~raw_os_ostream() {
+  flush();
+}
+
+void raw_os_ostream::write_impl(const char *Ptr, size_t Size) {
+  OS.write(Ptr, Size);
+}
+
+uint64_t raw_os_ostream::current_pos() const { return OS.tellp(); }