ssa_log.c: Set flog pointer to NULL after fclose in ssa_close_log

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa_log.c: Avoid closing stderr or stdout in ssa_close_log

SSA may use stderr or stdout for log. If an application
uses stderr or stdout after, this will likely crash the application
in unexpected way.

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
[core distrib acm]: Move ssa log closing after cleanup

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>