Merge branch 'lsfd--bpf-name#in-flight' of https://github.com/masatake/util-linux

Merge branch 'lsfd--bpf-name#in-flight' of https://github.com/masatake/util-linux

* 'lsfd--bpf-name#in-flight' of https://github.com/masatake/util-linux:
  tests: (lsfd) extend the cases for testing BPF.NAME column
  lsfd.1.adoc: document BPF.NAME column
  lsfd: add BPF.NAME column
  lsfd: add xstrfappend and xstrvfappend
  lib/strutils: add strfappend and strvfappend
  tests: (test_mkfds::{bpf-prog,bpf-map}) fix memory leaks
  tests: (test_mkfds) add missing PARAM_END marker
  tests: (test_mkfds) use SYS_bpf instead of __NR_bpf
  tests: (test_mkfds) revise the usage of " __attribute__((__unused__))"
  tests: (lsfd::mkfds-bpf-map) chmod a+x