config: remove insecure warnings

config: remove insecure warnings

There was an option CONFIG_RTE_INSECURE_FUNCTION_WARNING (disabled by
default), which prevents from using some libc functions:
sprintf, snprintf, vsnprintf, strcpy, strncpy, strcat, strncat, sscanf,
strtok, strsep and strlen.

It's all about using them at the right place with the right precautions.
However, it is neither really possible nor a good advice to disable them.

Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>