logging extend level set api to allow setting emission function

Signed-off-by: Andy Green <andy.green@linaro.org>
logging add timestamp

Signed-off-by: Andy Green <andy.green@linaro.org>
audit and make all malloc check for OOM

Signed-off-by: Andy Green <andy.green@linaro.org>
introduce getifaddrs for toolchains without it

David found that uclibc did not provide this slightly esoteric api
and provided one from BSD that can be built by the library internally.

AG: Made contingent on configure option --enable-builtin-getifaddrs

Signed-off-by: David <cymerio@gmail.com>
Signed-off-by: Andy Green <andy.green@linaro.org>
fix config enable name for getifaddrs

copy-paste...

Signed-off-by: Andy Green <andy.green@linaro.org>
renable deflate frame buffer expansion fixing DoS

This reverts the removal of the deflate_frame code that was crashing after porting
David Galeano's code: he pointed out there's a typo in the merged version causing
the crash which is fixed here.

However the fixed code has a problem, there's no limit (other than int size) to the
amount of memory it will try to malloc, which can allow a DoS of the server by the
client sending malicious compression states that inflate to a large amount.  I have
added checking for OOM already that will avert the segfault that would otherwise follow
but the server will be unusuable if malicious connections were made repeatedly each
forcing it to allocate large buffers and cause small allocations on other connections
to fail.

The patch changes the code to use realloc(), and introduces a configurable limit
on the amount of memory one connection may need for zlib before the server hangs
up the connection.  It defaults to 64KBytes but can be set from ./configure as
described now in the README.

Signed-off-by: Andy Green <andy.green@linaro.org>
expose compiletime constants to setting from configure

This patch allows control of the main compiletime constants in libwebsockets
from the configure commandline.

README is updated with documentation on what's available, how to set them
and the defaults.

The constants are logged with "info" severity (not visible by default) at
context create time.

The zlib constant previously exposed like this is moved to private-libwebsockets.h
so it can be printed along with the rest.

Signed-off-by: Andy Green <andy.green@linaro.org>