Merge branch 'depcomp-work'

Merge branch 'depcomp-work'

* depcomp-work:
  depcomp: remove 'icc' depmode, add 'tcc' one
  news: update w.r.t. recent depcomp changes
  tests: fix spurious failures with tcc
  depcomp: improve comments about tcc support
  depcomp: remove last relics of libtool 1.4 support
  depcomp: remove an unused variable
  depcomp: rewrite a sed invocation for less quoting
  depcomp: whitespace fixes
  depcomp: shell code style changes
  depcomp: make some code more self-documenting
  depcomp: less duplication between AIX and Tru64 modes
  depcomp: avoid an extra fork when possible
  depcomp: reduce code duplication
  depcomp: don't rely on character ranges working as in C locale
  depcomp: cosmetic fixlets to a comment
  depcomp: safer quoting in variable expansion
  depcomp: correctly propagate exit status in exit trap
  depcomp: use "rmdir", not "rm -rf", to remove the empty lock directory
  depcomp: remove useless quoting in variable definitions
  depcomp: be more idiomatic in checking for zero exit statuses