plugin/Makefile.am: Add some missing files to EXTRA_DIST

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
distrib/Makefile.am: Add install-exec-hook and some missing files to EXTRA_DIST

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
plugin/Makefile.am: Removed redundant commented out line

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