Merge tag 'kgdb-fixes-4.20-rc3' of https://git.linaro.org/people/daniel.thompson...

Pull kgdb fixes from Daniel Thompson:
 "The most important changes here are two fixes for kdb regressions
  causes by the hashing of %p pointers together with a fix for a
  potential overflow in kdb tab completion handling (and warning fix).

  Also included are a set of changes in preparation to (eventually)
  enable -Wimplicit-fallthrough"

* tag 'kgdb-fixes-4.20-rc3' of https://git.linaro.org/people/daniel.thompson/linux:
  kdb: kdb_support: mark expected switch fall-throughs
  kdb: kdb_keyboard: mark expected switch fall-throughs
  kdb: kdb_main: refactor code in kdb_md_line
  kdb: Use strscpy with destination buffer size
  kdb: print real address of pointers instead of hashed addresses
  kdb: use correct pointer when 'btc' calls 'btt'