distrib.c: remove unnecessary comment

Signed-off-by: Ilya Nelkenbaum <ilyan@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
plugin/core.c: name changes

The following changes were done:
 - 'fd' socket used for communication between main core thread
    and extract thread was changed to 'sock_coreextract'
 - 'ssa_db_run' method was changed to 'ssa_extract_handler'
 - 'smdb_extract_thread' was changed to 'extract_thread'

Signed-off-by: Ilya Nelkenbaum <ilyan@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
plugin/core.c: changing local 'p_ssa_db_diff' to be global 'ssa_db_diff'

Signed-off-by: Ilya Nelkenbaum <ilyan@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>