Add a simple C++ file wrapper class.

Add a simple C++ file wrapper class.

This helps in writing exception-safe code, and also takes care of error
reporting (using exceptions).  Currently only a minimal implementation,
but more methods can be added when needed.

Also made a minor adjustmend to the internal boost to avoid compiler
warnings.

Change-Id: I751f1ad242e7f94d06a9165dcca57525b6a99c96