tm: execute FAILURE_CB_TYPE callbacks for resuming suspended request

- suspended request creates the transaction and a branch, callbacks
  cannot executed anymore for request and branch route execution
- otherwise it results in crashes, reported by FS#400 and FS#404

(cherry picked from commit 78c8eb1fa4b118661262fd6add9a0e9f60ca8cd1)
tm: declare variable at the top of function declaration in t_suspend()

- compliant with older versions of C standards
- simpliefied log messages

(cherry picked from commit dce7353674ea3d93ade93c89bbb4652e7ec624be)