Add streaming base64 CBOR encoder to libutils

This implements an encoder for the Concise Binary Object Representation
that is streamed to an output as a base64 encoded bytestream.

For more details on CBOR, see [IETF RFC
7049](https://tools.ietf.org/html/rfc7049).

Signed-off-by: Curtis Millar <curtis.millar@data61.csiro.au>

trivial: Style changed files

libutils: Add next-power-of-2 macro

Like the name suggests, this macro calculates the next power of 2 for a
32 bit integer.

libutils: MASK can create masks that are all 1's

By using two operations of MASK_UNSAFE and BIT a full mask of 1's is able to be created.

fix licenses

Add DIV_ROUND and DIV_ROUND_UP macros

libutils: trivial: Replace ifdef guards with pragma once.

libutils: Remove unnecessary use of GNU statement expression.

libutils: Fix double expansion of expression within macro.

A macro designed to only expand its arguments once is decidedly unhelpful when
it doesn't do such.

libutils: Added 'PAD_STRUCT_BETWEEN' macro

This macro generates dummy struct fields that add padding to structs. It
is useful when a struct must correspond to a register layout, such as in
a device driver.

libutils: Fix: more portable LOG_BASE_2 macro.

The previous definition of this macro used `typeof` on the input parameter,
ignoring the fact that the input is promoted to an `unsigned long` in the
course of being passed to `__builtin_clzl`. The new definition also takes into
account platforms where a byte is not 8 bits (almost nowhere, but doesn't hurt
to be paranoid) and removes some extraneous brackets.

Closes GINCA #13

libutils: Comments explaining MASK and LOG_BASE_2 macros

libutils: Add long versions of bit operations and preference using them

libutils: Use 64-bit friendly types