Preparation for initialization of negative cache in common responder.

Reviewed-by: Pavel Březina <pbrezina@redhat.com>

Push/pop global_talloc_context into check_leaks is redudant. It is done
in leak_check_setup() and leak_check_teardown() functions in
src/tests/check_leaks.

Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>

It will compilation of 40 files.

Reviewed-by: Pavel Březina <pbrezina@redhat.com>

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

Adds support to get SELINUX context and make code more abstract so
that struct ucred (if availale) can be used w/o redefining uid,gid,pid to
int32. Also gives a layer of indirection that may come handy if we want
to improve the code further in the future.

Signed-off-by: Lukas Slebodnik <lslebodn@redhat.com>
Reviewed-by: Michal Židek <mzidek@redhat.com>

Reviewed-by: Petr Cech <pcech@redhat.com>

If leak_check_setup is not called then global_talloc_context
was not initialized and check_leaks_pop(global_talloc_context) will fail.

Reviewed-by: Petr Cech <pcech@redhat.com>

The similarcahnge was done in main makefile by change
69b46c32357ccf1aab9c0bd6d1afa33a8724ad77

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

LIBCAPNG_{CFLAGS,LIBS} are not defined anywhere in sssd.
It could be introduced as copy&paste error from different project.

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

responder_common_tests does not use any function which requires to link
with UNICODE linraries or with libsss_crypt

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>