Resubmit r301986 and r301987 "Add codeview::StringTable"

This was reverted due to a "missing" file, but in reality
what happened was that I renamed a file, and then due to
a merge conflict both the old file and the new file got
added to the repository.  This led to an unused cpp file
being in the repo and not referenced by any CMakeLists.txt
but #including a .h file that wasn't in the repo.  In an
even more unfortunate coincidence, CMake didn't report the
unused cpp file because it was in a subdirectory of the
folder with the CMakeLists.txt, and not in the same directory
as any CMakeLists.txt.

The presence of the unused file was then breaking certain
tools that determine file lists by globbing rather than
by what's specified in CMakeLists.txt

In any case, the fix is to just remove the unused file from
the patch set.

llvm-svn: 302042

llvm/lib/Support/BinaryStreamReader.cpp

@@ -93,3 +93,16 @@ uint8_t BinaryStreamReader::peek() const {
   llvm::consumeError(std::move(EC));
   return Buffer[0];
 }
+
+std::pair<BinaryStreamReader, BinaryStreamReader>
+BinaryStreamReader::split(uint32_t Off) const {
+  assert(getLength() >= Off);
+
+  BinaryStreamRef First = Stream.drop_front(Offset);
+
+  BinaryStreamRef Second = First.drop_front(Off);
+  First = First.keep_front(Off);
+  BinaryStreamReader W1{First};
+  BinaryStreamReader W2{Second};
+  return std::make_pair(W1, W2);
+}