htp layer: use memcap for HTTP related allocations

This patch introduces wrapper functions around allocation functions
to be able to have a global HTP memcap. A simple subsitution of
function was not enough because allocated size needed to be known
during freeing and reallocation.

The value of the memcap can be set in the YAML and is left by default
to unlimited (0) to avoid any surprise to users.
htp layer: add memory usage counter

This patch adds a memory counter for HTP memory usage. As
there is no thread variables available in application layer
the counter has been added to the TCP reassembly thread.
htp layer: add memory cap counter

This patch adds a memcap counter for HTP memory usage. Counter
is increased each time an allocation is not done due to the memcap.
prscript: add --norebase option

If --norebase option is provided, the prscript will start a build
that can be used to check if an out-of-sync branch pass the test.
af-packet: update packet reading loop logic

This patch updates the logic of the packet acquisition loop. When
the reader loop function is called and when the data to read
at offset is a without data (kernel) or still used by suricata. We
try to iter for a loop on the ring to try to find kernel put by
data.
As we are entering the function because the poll said there was some
data. This allow us to jump to the data added to the ring by the
kernel.
When using suricata in autofp mode, with multiple detect threads and
packet acquisition threads attached to a dedicated CPU, the reader
loop function was looping really fast because poll call was returning
immediatly because we did read the data available.
Add missing UNITTESTS

There is no need for test functions to be build in normal code.
doxygen: add profiling to generated doc.

Profiling code needs the PROFILING define to be documented.
doxygen: document all code

This patch update doxygen configuration to have all possible functions
documented (even the one without doxygen formated comments). It can be
really useful to have that in case we are trying to get some information
on call graph for example.
doxygen: document some functions
debug: default logging level is notice

Update the string in message because default logging level is
now notice and not info.
Correct coding style in decode-ethernet.c

This file is given as the example of correct coding style, so make sure it
follows the coding standard.