Export the spdk_set_thread(), so that apps may use it to associate
a thread with SPDK thread when necessary.
Change-Id: I488bea639729d68d7261a497085bbec274357224
Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/461509
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>