This change will allow external libs to register SPDK log flags and use log macros by external libs. Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com> Change-Id: I03ef088580bbf23bd22ad1a36817ca84c5ba8edd Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/3954 Tested-by: SPDK CI Jenkins <sys_sgci@intel.com> Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com> Reviewed-by: Ben Walker <benjamin.walker@intel.com>