libev protect when disabled at runtime in server.c

Signed-off-by: Andy Green <andy.green@linaro.org>
only use clean buffer for failed write if sent something

Signed-off-by: Andy Green <andy.green@linaro.org>
truncated send issue independent of LWS_NO_EXTENSIONS

Signed-off-by: Andy Green <andy.green@linaro.org>
truncated send issue independent of LWS_NO_EXTENSIONS 2

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