[ctf] Fix coding style issues in BitBuffer.

[ctf] Fix coding style issues in BitBuffer.

Fix potential issue with an undefined behavior in CTF.
 - Reading a integer of zero bit at the end of the buffer may be valid.
 - Change the behavior to accept it.

Change-Id: I22fccc4e2ffee3bbf796e52b516b00f7fc5e31ac
Signed-off-by: Etienne Bergeron <etienne.bergeron@gmail.com>
Reviewed-on: https://git.eclipse.org/r/18707
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Tested-by: Hudson CI
Reviewed-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
IP-Clean: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Tested-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>